Day 1 chapter 1 Know our numbers

1. Delhi Public School
Class VI Mathematics
Chapter 1 – Knowing our Numbers
Day 1

2. • Natural numbers- The counting numbers 1,2,3,4,5,…………..are
known as natural numbers. Natural number system starts with ‘1’
and it goes on endlessly as there are infinite numbers.
• Whole numbers – The natural numbers together with ‘0’ are called
the whole numbers, which means that 0,1,2,3,……….etc. are called
whole numbers.
• THERE ARE TWO METHODS OF NUMERATION
• Indian System
• International System

3. Indian system of Numeration
• Indian place value chart for 9-digit number
• How will Twenty three crore ninety eight lakh seventy six thousand
five hundred six be shown in the Indian System ?
which means we have to write 239876506 in the Indian System
Crores Lakhs Thousands Ones Period
TC C TL L TTH Th H T O Place
2 3 9 8 7 6 5 0 6

4. International system of Numeration
• International place value chart for a 9 digit number
• How will Two hundred thirty nine million eight hundred seventy six
thousand five hundred six be shown in the International System?
which means we have to write the same number, 239876506 in the
International System
Millions Thousands Ones Period
HM TM M HTh TTh Th H T O Place
2 3 9 8 7 6 5 0 6

5. Inserting Commas
• Inserting commas helps in reading and writing large numbers. A comma is
inserted after each period in both the systems.
• We do not use commas while writing number names
• Commas are used only to mark periods
• In Indian system of numeration
• First comma mark comes after hundred’s place (3 digits from the right)
• Next comma comes after every two digits
• Example – 23,98,76,506
• In International system of numeration
• Comma comes after every three digits from the right
• Example – 239,876,506

6. Place value and Face value
• Place value of a digit in a number is the digit multiplied by its place.
• Face value of a digit remains the same, whatever place it may be
occupying in the place value chart. In other words, face value is the
actual value of the digit.
• For example – in 2,35,769
• 2 is the face value of the extreme left digit
• Place value of the same digit is 2 lakh
• And so on…

7. Arranging Numbers
• Ascending and Descending order
• Numbers can be arranged in ascending or descending order.
• Ascending order means arrangement from smallest to the greatest.
• Descending order means arrangement from largest to smallest.
• Greatest ‘n’ digit number (where n = 1,2,3….) + 1 = Smallest (n + 1) digit
number
• Example - The greatest six-digit number is 999999. When we add 1 to this six-digit
number, we get 10,00,000, which is the smallest seven-digit number.
• The number which is one more than the given number is called its
successor.
• The number which is one less than the given number is called its
predecessor.

8. Examples
• How many thousands make a lakh?
• Solution:
100000
1000
=
1 𝑙𝑎𝑘ℎ
1 𝑡ℎ𝑜𝑢𝑠𝑎𝑛𝑑
= 100 .
• So, we can say that 100 thousands make a lakh.
• How many 4-digit numbers are there in all?
• Solution: Greatest 4 digit number = 9999
• Smallest 3-digit number = -999
_________
• 4-digit numbers in all 9000

9. Examples
• Write the greatest and smallest 4-digit numbers by using any one digit
twice:
(a) 4,8,9 (b) 4,0,6
Solution: Using digits 4,8,9 Solution: Using digits 4,0,6
Greatest 4-digit number =9984 Greatest 4-digit number= 6640
Smallest 4-digit number =4489 Smallest 4-digit number= 4006

10. Assignment:
• In each of the following, write the place value of the underlined digit:
• 73,02,549
• 123,456,789
• 10,265,930
• Find the sum of the face value and place value of digit 3 in the number 93278
• Place commas correctly and write the numerals for the following:
• Ninety-seven lakh fifty-three thousand fifteen
• Seventy-three crore five lakh eighty-five thousand three hundred five
• Sixty-two lakh eight
• Six million seven hundred eighty-two thousand two hundred six
• Six hundred sixty-six million six hundred six hundred thousand sixty six
• Write the greatest and smallest 4-digit number using different digits with
• Digit 7 in hundred’s place
• Digit 1 in thousand’s place
• Write the following number in expanded form
• 6,89,205
• 153,968
• 10,265,930