Math for Smart Kids Gr.2

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Diwa Textbooks - Math for Smart Kids Grade 2

Math for Smart Kids is the grade school textbook which features online exercises in www.diwalearningtown.com to complement review of textbook lessons. The book addresses the learning needs in mathematics such understanding and skills in computing considerable speed and accuracy, estimating, communicating, thinking analytically and critically, and in solving problems using appropriate technology.

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Math for Smart Kids Gr.2

  1. 1. Math for Smart Kids 2
  2. 2. Math for Smart KidsGrade 2TextbookPhilippine Copyright 2010 by DIWA LEARNING SYSTEMS INCAll rights reserved. Printed in the PhilippinesEditorial, design, and layout by University Press of First AsiaNo part of this publication may be reproduced or transmitted in any form or by any means electronic ormechanical, including photocopying, recording, or any information storage and retrieval systems, withoutpermission in writing from the copyright owner. Exclusively distributed by DIWA LEARNING SYSTEMS INC 4/F SEDCCO 1 Bldg. 120 Thailand corner Legazpi Streets Legaspi Village, 1229 Makati City, Philippines Tel. No.: (632) 893-8501 * Fax: (632) 817-8700 ISBN 978-971-46-0117-8The Editorial BoardAuthorsDr. Estrella P. Mercado finished her PhD in Educational Management (with honor) and MA in Education at ManuelL. Quezon University. She also holds an MEd in Special Education degree and a BS in Elementary Education degreefrom the Philippine Normal University (PNU). She has been a classroom teacher, an Education supervisor, andassistant chief of the Elementary Division of the Department of Education, Culture and Sports (DECS-NCR). She wasawarded as Outstanding Female Educator in 1998 by the Filipino Chinese Women Federation. She presently heads theSpecial Education Department at PNU.Jasmin Iris F. Sallegue graduated cum laude from PNU with a degree in Bachelor of Secondary Education majorin Mathematics. She is currently a grade school Mathematics teacher at De La Salle Santiago Zobel School in AyalaAlabang. She has trained students of De La Salle Santiago Zobel School for various mathematics competitions, likethe annual Metrobank-MTAP-DepEd Math competition. She is a member of the Mathematics Teachers Associationof the Philippines (MTAP).Consultant-ReviewerLuzviminda M. Sibbaluca holds a master’s degree in Mathematics Education and a bachelor’s degree in ElementaryMathematics Education (cum laude) both from the University of the Philippines-Diliman. She is one of the top tensuccessful examinees of the Licensure Examination for Teachers (LET) for Elementary in 2003. She is currently anassistant professor at the Mathematics Department of the University of the Philippines Integrated School (UPIS).
  3. 3. Preface Math for Smart Kids is a series of textbooks in Mathematics forgrade school, which is designed to help pupils develop appreciationand love for mathematics. This series also aims to help the learnersacquire the skills they need to become computationally literate. The lessons in each textbook present mathematics concepts andprinciples that are anchored on the competencies prescribed by theDepartment of Education. Each lesson starts with Let’s Do Math,where mathematics concepts and principles are introduced throughproblems, stories, games, or puzzles. This section is followed by Let’sLook Back, which lists questions that will help the pupils to thinkcritically on what has been introduced in the lesson and will allowthem to discover things on their own. For easy recall of importantpoints or concepts taken up in a lesson, the section Let’s RememberOur Learning has been included. Multilevel exercises are provided inLet’s Practice and Let’s Test Our Learning that will assess how muchthe pupils have learned from the lesson. The exercises will alsodetermine if the pupils are ready to learn new mathematics skills. Thedevelopment of the multiple intelligences of an individual is reflectedin the different activities that the pupils will perform—from concreteto semi-concrete, and from semi-abstract to abstract kind of learning.Situations and real-life problems are provided in Let’s Look Forward togive the pupils opportunities to apply what they have learned to theirdaily life experiences. This series of textbooks gives the learners the opportunity toexplore and enjoy Mathematics. Let’s have fun learning together! The Authors
  4. 4. Table of ContentsUnit 1 Comprehension and Addition of Whole NumbersChapter 1 Numbers through Ten ThousandsLesson 1 Numbers through 500 .................................................... 2 2 Numbers Up to Thousands ............................................ 9 3 Ordinal Numbers......................................................... 16 4 Place Values through Ten Thousands ........................... 21 5 Reading and Writing Numbers through Ten Thousands ............................................... 25 6 Comparing and Ordering Numbers .............................. 30 7 Rounding off Numbers ................................................ 37 8 Reading and Writing Money Values ............................. 41 9 Roman Numerals ......................................................... 48Chapter 2 Addition of Whole NumbersLesson 1 Properties of Addition.................................................. 53 2 Adding Three-digit Numbers ....................................... 57 3 Adding Four- to Five-digit Numbers ............................. 64 4 Adding Three or More Addends .................................. 69 5 Estimating Sums .......................................................... 74 6 Solving Word Problems on Addition of Whole Numbers ..................................................... 78Unit 2 Subtraction, Multiplication, and Division of Whole NumbersChapter 3 Subtraction of Whole NumbersLesson 1 Subtracting Two- to Three-digit Numbers ................... 84 2 Subtracting Four-digit Numbers with Zeros in the Minuend ........................................................... 92
  5. 5. 3 Estimating Differences ................................................ 97 4 Solving Word Problems on Subtraction of Whole Numbers ....................................................100 5 Combined Operations: Addition and Subtraction ................................................................104 6 Solving Two-step Word Problems ..............................108Chapter 4 Multiplication of Whole NumbersLesson 1 Understanding Multiplication ....................................112 2 Properties of Multiplication .......................................119 3 Multiplying One-digit Numbers .................................124 4 Multiplying Two- to Three-digit Numbers by One-digit Numbers ...............................................128 5 Solving Word Problems on Multiplication of Whole Numbers ....................................................132 6 Series of Operations: Multiplication, Addition, and Subtraction ..........................................136 7 Solving Multistep Word Problems ..............................140Chapter 5 Division of Whole NumbersLesson 1 Understanding Division .............................................145 2 Dividing Two-digit Numbers by One-digit Numbers ...............................................150 3 Dividing Three-digit Numbers by One-digit Numbers ...............................................154 4 Solving Word Problems on Division of Whole Numbers ....................................................158 5 Series of Operations ...................................................162 6 Solving Two-step Word Problems ..............................165Unit 3 Fractions and GeometryChapter 6 FractionsLesson 1 Fraction as Part of a Whole and a Set ..........................170 2 Reading and Writing Fractions ................................... 175
  6. 6. 3 Fractional Part of a Set................................................181 4 Comparing Fractions ..................................................187 5 Ordering Fractions......................................................192Chapter 7 GeometryLesson 1 Polygons and Circles ..................................................196 2 Symmetry ..................................................................200 3 Tessellation ...............................................................204 4 Space Figures ............................................................207Unit 4 Measurement, Time, and GraphsChapter 8 MeasurementLesson 1 Standard Units of Linear Measurement .......................212 2 Perimeter ...................................................................219 3 Area ..........................................................................225 4 Mass ..........................................................................232 5 Capacity ....................................................................237Chapter 9 TimeLesson 1 Concept of Time ........................................................241 2 Days of the Week ......................................................246 3 Months of the Year ....................................................248Chapter 10 GraphsLesson 1 Pictograph .................................................................251 2 Bar Graph .................................................................256 3 Making a Pictograph and a Bar Graph .......................261Bibliography ......................................................................................266
  7. 7. UnitComprehension andAddition of WholeNumbers
  8. 8. Chapter 1 Numbers through Ten Thousands Lesson 1 Numbers through 500 Forms of Writing Numbers Mang Arman harvested 133 chicos last Monday. The total number of chicos can be shown as: 100 30 3 A number can be written in three forms: Standard form : 133 Expanded form : 100 + 30 + 3 = 133 Word form : one hundred thirty-three To write a number in expanded form, write an addition sentence using the values of the digits. Math for Smart Kids 2
  9. 9. Look at this next example. Aling Nelia ordered 245 eggs for her bakery. 100 100 200 40 5 Standard form : 245 Expanded form : 200 + 40 + 5 = 245 Word form : two hundred forty-fiveSkip Counting Skip counting can be done by 2s, 5s, 10s, 20s, through 100s. Look at the number table below. The encircled numbers showskip counting by 10s. Use the same table to skip count by 5s and 20s. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 Comprehension and Addition of Whole Numbers
  10. 10. Comparing Numbers Aiza found 50 buttons in her mother’s cabinet. Issa found 40 buttons in the cabinet, too. Who found more buttons? Compare the number of buttons found by the two girls. Aiza Issa 50 40 5 is greater than 4. So 50 is greater than 40. In symbols, 50 40 So Aiza found more buttons. Here are other examples of comparing numbers through 500: 160 150 because 6 is greater than 5 230 240 because 3 is less than 4 425 = 425 because the digits of both numbers are the same In comparing numbers, start comparing the digits in the highest place value. If the digits are the same, compare the digits in the next place value. Numbers can be compared using the symbols = (equal to), (greater than), and (less than). Ordering Numbers Arrange the numbers in increasing or ascending order. 435 391 439 392 Start by comparing two numbers at a time. Math for Smart Kids 2
  11. 11. 391 392 435 439 392 435 To arrange the numbers in ascending order, arrange themfrom least to greatest. Ascending order: 391, 392, 435, 439 1. What are the three forms of writing a number through 500? 2. How do you compare numbers up to hundreds? 3. How do you arrange numbers in ascending order? Numbers through 500 may be written in different forms. Standard form: 263 Expanded form: 200 + 60 + 3 = 263 Word form: two hundred sixty-three To compare numbers, start comparing the digits in the highest place value. If the digits are the same, compare the digits in the next place value. To arrange numbers in ascending order, compare them two at a time. Then arrange them from the least to the greatest. Comprehension and Addition of Whole Numbers
  12. 12. A. Write the following in standard form. 1. eighty-five ______________ 2. thirty-two ______________ 3. fifty-six ______________ 4. three hundred eighty-seven ______________ 5. four hundred ninety-one ______________ B. Write the following numbers in word form. 1. 92 ______________________________________________ 2. 184 ______________________________________________ 3. 271 ______________________________________________ 4. 58 ______________________________________________ 5. 443 ______________________________________________ C. Study the skip counting pattern. Fill in the blanks with the correct numbers. 1. 5, 10, 15, ____, ____ 4. 50, 100, 150, ____, ____ 2. 20, 40, ____, 80, 100, ____ 5. 60, 70, ____, ____, 100 3. 10, 20, 30, ____, ____ 6. 100, 200, ____, 400, ____ D. Compare the numbers. Write , , or = on the blank space. 1. 75 ___ 80 6. 98 ___ 97 2. 92 ___ 84 7. 400 + 80 + 1 ___ 81 3. 30 + 2 ___ 32 8. 50 + 8 ___ 58 4. 40 + 7 ___ 46 9. 200 + 5 ___ 30 + 5 5. 81 ___ 85 10. 395 ___ 397 Math for Smart Kids 2
  13. 13. Get your total score in parts A to D of Let’s Practice. Writethe number in standard, expanded, and word forms.A. Encircle the letter of the correct answer. 1. What number is greater than 57? a. 46 b. 48 c. 58 2. What number is less than 40? a. 38 b. 94 c. 56 3. What number is equal to 90 + 4? a. 92 b. 94 c. 49 4. What is the missing number: 5, 10, 15, ___? a. 20 b. 25 c. 30 5. What is the missing number: 20, 30, ___, 50? a. 35 b. 40 c. 55 6. What is the missing number: 50, ___, 150, 200? a. 100 b. 250 c. 300 7. What is the standard form of two hundred seventy-eight? a. 277 b. 278 c. 280 8. What is the standard form of forty-seven? a. 45 b. 46 c. 47 9. How do you write 91 in word form? a. eighty-one b. ninety-one c. ninety-two 10. How do you write 69 in word form? a. sixty-six b. ninety-six c. sixty-nine Comprehension and Addition of Whole Numbers
  14. 14. B. Compare the numbers. Write , or = on the blank space. 1. 100 + 60 + 3 ___ 100 + 50 + 3 2. 300 + 40 + 5 ___ 300 + 40 + 1 3. 400 + 80 + 4 ___ 484 4. 492 ___ 400 + 800 + 2 5. 275 ___ 200 + 70 + 5 C. Arrange the numbers in each set in ascending order. Write the numbers 1–4 (1 – least number, 4 – greatest number) on the blank spaces. 1. 163 136 123 132 ___ ___ ___ ___ 2. 271 281 217 218 ___ ___ ___ ___ 3. 349 319 394 314 ___ ___ ___ ___ 4. 401 421 410 412 ___ ___ ___ ___ 5. 457 407 437 417 ___ ___ ___ ___ Math for Smart Kids 2
  15. 15. Lesson 2 Numbers Up to Thousands Andrew is a postman. He delivered 2 164letters to houses in Cupang, Muntinlupa City. The number 2 164 can be shown as: 2 000 100 60 4 You can write the number in expanded form, 2 164 = 2 000 + 100 + 60 + 4 and in word form, two thousand, one hundred sixty-four. Comprehension and Addition of Whole Numbers
  16. 16. Skip Counting Study the patterns of numbers below. 1. 10, 20, 30, 40, 50, 60, 70, 80, 90 2. 100, 200, 300, 400, 500, 600, 700, 800, 900 3. 500, 1 000, 1 500, 2 000, 2 500, 3 000, 3 500, 4 000 4. 1 000, 2 000, 3 000, 4 000, 5 000 What skip counting pattern is shown in each set of numbers? The first set shows skip counting by 10s. The second set shows skip counting by 100s. The third set shows skip counting by 500s. The last set shows skip counting by 1 000s. Comparing Numbers Ifugao has a total land area of 2 517 square kilometers. Ilocos Sur has a total land area of about 2 579 square kilometers. Which province has a greater land area ? 2 579 2 517 because the digit 7 is greater than the digit 1. To compare numbers up to thousands, start comparing the digits in the thousands place. The greater digit shows the greater number. Ordering Numbers These are the land areas (in square kilometers) of four provinces in Luzon. Quirino – 3 057 Batangas – 3 166 Tarlac – 3 053 Kalinga – 3 07110 Math for Smart Kids 2
  17. 17. Arrange the land areas of the four provinces in descendingorder. Start by comparing two numbers at a time. 3 166 3 071 3 057 3 053 3 071 3 057 To arrange numbers in descending order, arrange them fromgreatest to least. 3 166 3 071 3 057 3 053 Batangas Kalinga Quirino Tarlac 1. How do you skip count by 500s and 1 000s? 2. How do you compare and order numbers up to thousands? Numbers up to thousands can be written in different forms. Standard form: 2 164 Expanded form: 2 000 + 100 + 60 + 4 = 2 164 Word form: two thousand, one hundred sixty-four To compare numbers up to thousands, start comparing the digits in the thousands place. The greater digit shows the greater number. To arrange numbers in descending order, arrange them from greatest to least. Comprehension and Addition of Whole Numbers 11
  18. 18. A. Study the pictures. Write the numbers in three different forms. 1. 10 1 000 100 10 10 Standard form: _____________ Expanded form: ___________________________________ Word form: _______________________________________ 2. 100 10 1 000 10 100 Standard form: ______________ Expanded form: ___________________________________ Word form: _______________________________________ 3. 1 000 Standard form: _______________ Expanded form: ___________________________________ Word form: _______________________________________1 Math for Smart Kids 2
  19. 19. B. Write the following in standard form. 1. one thousand, two hundred three __________ 2. two thousand, one hundred thirty-two __________ 3. two thousand, four hundred forty-five __________ 4. three thousand, three hundred twenty-six __________ 5. four thousand, two hundred __________ 6. six thousand, nine hundred fifty-one __________C. Write the following in word form. 1. 5 400 ____________________________________________ 2. 6 326 ____________________________________________ 3. 7 423 ____________________________________________ 4. 8 546 ____________________________________________ 5. 9 227 ____________________________________________ 6. 4 639 ____________________________________________ Write the last digit of your birth year. For example, if youwere born in 2001, you will write 1. Write beside this digitthe number of your birth month. For January, write 01; forFebruary, write 02; and so on. Then, write your favorite one-digit number beside these numbers. What number did you form? Write the number in standard,expanded, and word forms. Then compare your number withthe number formed by your seatmate. Who has the greaternumber? Comprehension and Addition of Whole Numbers 1
  20. 20. A. Write the following in word form. 1. 1 342 ____________________________________________ 2. 5 295 ____________________________________________ 3. 3 433 ____________________________________________ B. Change the given forms of numbers in standard form. Then compare the numbers. Write , , or = in the box. 1. one thousand, six hundred 1 000 + 600 + 2 twenty 2. two thousand, seventy-eight 2 000 + 700 + 80 + 8 3. two thousand, four hundred 2 000 + 400 + 60 + 1 sixty-one 4. three thousand, nine hundred 3 000 + 900 + 60 + 1 sixteen 5. four thousand, five hundred five 4 000 + 50 + 51 Math for Smart Kids 2
  21. 21. C. Do what is asked for in each number. 1. Write the missing numbers in the . 100, 200, , 400, , 600, 700, , , 1 000 For exercises 2–4, refer to the numbers in the box. 3 516 2 709 2 178 3 672 2. Which numbers are less than 3 000? ___________________________________________________ 3. Which numbers are greater than 3 000? ___________________________________________________ 4. Arrange the numbers in ascending order. ___________________________________________________ 5. What number comes before and after 3 500 if you skip count by 500s? ___________________________________________________ Comprehension and Addition of Whole Numbers 1
  22. 22. Lesson 3 Ordinal Numbers Look at the objects. Counting from the left, the bag is the first, the pencil is the second, and the notebook is the third object. First, second, and third are called ordinal numbers. Ordinal numbers tell the positions of things or persons in an arrangement. Give the ordinal numbers for the objects shown above: school ID (counting from the left) _________ book (counting from the right) _________ crayon (counting from the left) _________ What are ordinal numbers?1 Math for Smart Kids 2
  23. 23. These are the ordinal numbers from 1st to 50th. 1st first 26th twenty-sixth 2nd second 27th twenty-seventh 3rd third 28th twenty-eighth 4th fourth 29th twenty-ninth 5th fifth 30th thirtieth 6th sixth 31st thirty-first 7th seventh 32nd thirty-second 8th eighth 33rd thirty-third 9th ninth 34th thirty-fourth 10th tenth 35th thirty-fifth 11th eleventh 36th thirty-sixth 12th twelfth 37th thirty-seventh 13th thirteenth 38th thirty-eighth 14th fourteenth 39th thirty-ninth 15th fifteenth 40th fortieth 16th sixteenth 41st forty-first 17th seventeenth 42nd forty-second 18th eighteenth 43rd forty-third 19th nineteenth 44th forty-fourth 20th twentieth 45th forty-fifth 21st twenty-first 46th forty-sixth 22nd twenty-second 47th forty-seventh 23rd twenty-third 48th forty-eighth 24th twenty-fourth 49th forty-ninth 25th twenty-fifth 50th fiftieth Ordinal numbers tell the positions or order of things orpersons in a given arrangement. Comprehension and Addition of Whole Numbers 1
  24. 24. A. Study the picture below. Tell the positions of the objects from left to right, and from right to left using ordinal numbers. From left to right From right to left 1. bottle ____________ _____________ 2. bowl ____________ _____________ 3. knife ____________ _____________ 4. glass ____________ _____________ 5. spoon ____________ _____________ 6. vase ____________ _____________ 7. cup ____________ _____________ 8. saucer ____________ _____________ 9. plate ____________ _____________ 10. fork ____________ _____________1 Math for Smart Kids 2
  25. 25. B. Box the animal for the given ordinal number. Count from left to right (→) and from top to bottom (↓). 1. 13th 2. 21st 3. 33rd Your teacher will post on the board the alphabetical list ofthe pupils’ names in your class. Tell your position on the list.Who is in the 10th position? Who is in the 20th position? Comprehension and Addition of Whole Numbers 1
  26. 26. A. Below are the letters of the Filipino alphabet. Write the letter that corresponds to each ordinal. A B C D E F G H I J K L M N Ñ NG O P Q R S T U V W X Y Z 1. 8th _______ 6. 10th _______ 2. 12th _______ 7. 27th _______ 3. 19th _______ 8. 14th _______ 4. 21st _______ 9. 26th _______ 5. 16th _______ 10. 22nd _______ B. Get a calendar. Then complete the sentences below. 1. Sunday is the first day of the week. ____________ is the second day. 2. Wednesday is the __________ day of the week. 3. Saturday is the ___________ day of the week. 4. January is the ___________ month of the year. 5. April is the ___________ month of the year. 6. December is the _________ month of the year. 7. The fifth month of the year is _______________. 8. My birth month is the ____________ month of the year.0 Math for Smart Kids 2
  27. 27. Lesson 4 Place Values through Ten Thousands Julie earns 18 725 every month. What is the place value of 8 in 18 725?What is the value of 2? To answer the questions, write thenumbers in a place-value chart.Place-value Chart Ten Thousands Thousands Hundreds Tens Ones 1 8 7 2 5 The chart shows the place values of the following digits: 1 – ten thousands 8 – thousands 7 – hundreds 2 – tens 5 – ones The place value of 8 in 18 725 is thousands. The value of 2is 20, since 2 tens is equal to 20. Place value tells the position of a digit in a number. Valueis the worth of a digit in a number. Comprehension and Addition of Whole Numbers 1
  28. 28. Study another example. What are the values of the two 8s in 98 480? Write the number in a place-value chart. Ten Thousands Thousands Hundreds Tens Ones 9 8 4 8 0 The chart shows that the place value of 9 is ten thousands; 8, thousands; 4, hundreds; 8, tens; and 0, ones. The values of the 8s in 98 480 are 8 000 and 80. This shows that the value of a digit depends on its place value. The place value of the leftmost digit 8 is thousands, so its value is 8 000. The place value of the rightmost digit 8 is tens, so its value is 80. 1. What are the place values of a four-digit number? 2. How is value related to place value? Place value tells the position of a digit, while value is the worth of a digit in a number. A place-value chart is used to show the place value and value of each digit in a number. The value of a digit depends on its place value. Math for Smart Kids 2
  29. 29. A. Write the place value of the underlined digit. 1. 13 428 _____________ 4. 18 759 ______________ 2. 16 921 _____________ 5. 34 785 ______________ 3. 29 243 _____________B. Write the value of the underlined digit. 1. 21 392 _________ 4. 27 656 _________ 2. 14 568 _________ 5. 39 497 _________ 3. 28 373 _________C. Find the mystery numbers. 1. My ones digit is 4. My thousands digit is twice my ones digit. My ten thousands digit is 2 less than my ones digit. My tens and hundreds digits are 1 more than my ten thousands digit. What number am I? 2. My hundreds digit is equal to 5 + 1. My ten thousands and tens digits are 3 less than my hundreds digit. My ones digit is twice my tens digit. My thousands digit is 2 more than my ones digit. What number am I? Ask for the last 5 digits of your telephone number at homeor your parent’s cell phone number. Write this number instandard and word forms. Then answer the following questions. 1. What is the value of the greatest digit? 2. What is the place value of the smallest digit? Comprehension and Addition of Whole Numbers
  30. 30. A. Write the place value and value of the underlined digit. Place Value Value 1. 14 672 ______________________ _____________ 2. 15 739 ______________________ _____________ 3. 32 487 ______________________ _____________ 4. 26 285 ______________________ _____________ 5. 48 343 ______________________ _____________ 6. 95 678 ______________________ _____________ 7. 39 280 ______________________ _____________ 8. 44 325 ______________________ _____________ 9. 97 829 ______________________ _____________ 10. 18 204 ______________________ _____________ B. Read carefully and solve. 1. My ten thousands digit is 8. My ones digit is 2 less than my ten thousands digit. My thousands digit is 4 less than my ones digit. My hundreds digit is 3 more than my ones digit. My tens digit is 7 less than my hundreds digit. What number am I? 2. My tens digit is 4. My ones digit is 2 more than my tens digit. My ten thousands digit is twice my tens digit. My hundreds digit is 3 less than my ten thousands digit. My thousands digit is 2 more than my hundreds digit. What number am I? 3. My hundreds digit is 4. My ones digit is 3 less than my hundreds digit. My ten thousands digit is 8 more than my ones digit. My thousands and tens digits are 3 more than my hundreds digit. What number am I? Math for Smart Kids 2
  31. 31. Lesson 5 Reading and Writing Numbers through Ten Thousands There were about 31 145delegates from differentcountries who participated inthe 2005 World Youth Day. When writing largenumbers, we separate theminto groups of three digitscalled periods. The periods of a number are separated with aspace or with a comma. Look at the place value chart below. It has two periods—theunits and thousands periods. The units period includes theones, tens, and hundreds digits. The thousands period includesthe thousands, ten thousands, and hundred thousands digits. Thousands Units Hundred Ten Thousands Hundreds Tens Ones Thousands Thousands 3 1 1 4 5 To read a large number, read the digits in the highest periodfirst. Mention the period’s name. Then read the digits in the nextperiod. Do not mention the period’s name for the units period. Thus, we read 31 145 as “thirty-one thousand, one hundredforty-five.” Comprehension and Addition of Whole Numbers
  32. 32. To write 31 145 in expanded form, write an addition sentence for the values of its digits. 31 145 = 30 000 + 1 000 + 100 + 40 + 5 How does a place-value chart help in reading large numbers? To read a number, read the digits in the highest period first and mention the period’s name. Then read the digits in the next period. Do not mention the period’s name for the units period. A. Read the number using the place-value chart. Write the word and standard forms of the number. 1. Thousands Units Ten Thousands Thousands Hundreds Tens Ones 2 7 9 4 2 Word form: ________________________________________ ________________________________________ Standard form: _____________________________________ Math for Smart Kids 2
  33. 33. 2. Thousands Units Ten Thousands Thousands Hundreds Tens Ones 3 6 8 2 2 Word form: ________________________________________ ________________________________________ Standard form: _____________________________________ 3. Thousands Units Ten Thousands Thousands Hundreds Tens Ones 4 9 8 1 3 Word form: ________________________________________ ________________________________________ Standard form: _____________________________________B. Write each number in expanded form. 1. 1 895 ___________________________________________ 2. 4 678 ___________________________________________ 3. 89 283 ___________________________________________C. Write the number word in standard and expanded forms. 1. fourteen thousand, five hundred sixty-two Standard form: ____________________________________ Expanded form: ___________________________________ 2. twenty-seven thousand, four hundred eighty-three Standard form: ____________________________________ Expanded form: ___________________________________ 3. thirty-nine thousand, three hundred seventy-six Standard form: ____________________________________ Expanded form: ___________________________________ Comprehension and Addition of Whole Numbers
  34. 34. 4. forty-six thousand, seven hundred ninety-seven Standard form: ____________________________________ Expanded form: ___________________________________ 5. fifty-eight thousand, six hundred fifty-four Standard form: ____________________________________ Expanded form: ___________________________________ Write the numbers in word and expanded forms. Do this on a separate sheet of paper. 98 942 27 831 14 374 A. Write each number in word and expanded forms. 1. 21 345 Word form: ________________________________________ Expanded form: ____________________________________ 2. 22 872 Word form: ________________________________________ Expanded form: ____________________________________ 3. 55 984 Word form: ________________________________________ Expanded form: ____________________________________ Math for Smart Kids 2
  35. 35. 4. 64 217 Word form: _______________________________________ Expanded form: ___________________________________ 5. 11 983 Word form: _______________________________________ Expanded form: ___________________________________B. Write each number in standard, word, and expanded forms.1. Thousands Units Ten Thousands Thousands Hundreds Tens Ones 1 9 1 9 9 Standard form: _______________________________________ Word form: __________________________________________ Expanded form: ______________________________________2. Thousands Units Ten Thousands Thousands Hundreds Tens Ones 3 6 9 2 4 Standard form: _______________________________________ Word form: __________________________________________ Expanded form: ______________________________________3. Thousands Units Ten Thousands Thousands Hundreds Tens Ones 6 4 0 3 9 Standard form: _______________________________________ Word form: __________________________________________ Expanded form: ______________________________________ Comprehension and Addition of Whole Numbers

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