Adding and Subtracting Decimals

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Step by step instruction on adding and subtracting decimals.

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Adding and Subtracting Decimals

  1. 1. Fifth Grade by Monica Yuskaitis, M.A.Ed. Decimals 2 Addition and Subtraction
  2. 2. For Learning to Happen! <ul><li>Clear your desk of anything that may </li></ul><ul><li>distract you. </li></ul><ul><li>Remove all other thoughts from your </li></ul><ul><li>mind. </li></ul><ul><li>Pay close attention. </li></ul><ul><li>Try all the examples. </li></ul><ul><li>Ignore all other distractions. </li></ul>
  3. 3. California Standard Addressed 1.1 Estimate, round, and manipulate very large and very small numbers. Number Sense Fifth Grade
  4. 4. California Standard Addressed 2.1 Add subtract, multiply, and divide with decimals;…and verify the reasonableness of the results. Number Sense Fifth Grade
  5. 5. California Standard Addressed 2.1 Use estimation to verify the reasonableness of calculated results. Math Reasoning Fifth Grade
  6. 6. California Standard Addressed 2.4 Express the solution clearly and logically by using the appropriate mathematical notation, terms, and clear language… Math Reasoning Fifth Grade
  7. 7. Objective <ul><li>To be able to add and subtract decimals. </li></ul>
  8. 8. Decimal Review
  9. 9. Decimals Represent Fractions <ul><li>6 8/10 3/100 6/1000 1/10,000 </li></ul>6 . 8 3 6 1 Tenths Hundredths Thousandths Notice that every decimal ends with “ths”. Ones Ten thousandths
  10. 10. Which decimal place value is missing? Hundredths Ones Tenths Hundredths 6 . 8 3 6 2 Ten Thousandths Thousandths
  11. 11. Which decimal place value is missing? Tenths Ones Tenths Hundredths 6 . 8 3 6 2 Ten Thousandths Thousandths
  12. 12. Which decimal place value is missing? Thousandths Ones Tenths Hundredths 6 . 8 3 6 2 Ten Thousandths Thousandths
  13. 13. Which decimal place value is missing? Ten Thousandths Ones Tenths Hundredths 6 . 8 3 6 2 Ten Thousandths Thousandths
  14. 14. How to Add Decimals
  15. 15. How to add decimals Line up the decimal points. Estimate. Write 0’s as needed. Compare sum with estimate. 1.23 4.797 1.23 4.797 1 2 3 Add. Write the decimal in the sum. 4 Estimate 6 Sum 6.027 0 1 5 6 + 7 2 1 0 1 . 6 1.23 4.797 0 +
  16. 16. Now it’s your turn to solve the problems.
  17. 17. Add these numbers 8 .6 6 + .7 = First line up the decimal points.
  18. 18. Add these numbers 6 0 + 6 3 9 .6 8 .7 1 .
  19. 19. Add these numbers 8 .7 5 + 6 .5 9 6 = First line up the decimal points.
  20. 20. Add these numbers 0 6 + 6 4 3 5 .7 9 1 8 .5 6 1 1 5 .
  21. 21. Add these numbers 5 + 8 .2 1 9 = First line up the decimal points.
  22. 22. Add these numbers .0 0 0 9 + 9 1 2 1 5 .2 8 1 3 .
  23. 23. How to Subtract Decimals
  24. 24. How to subtract decimals Line up the decimal points. Estimate. Write 0’s as needed. Compare answer with estimate. 8.74 3.679 8.74 3.679 1 2 3 Subtract. Write the decimal in answer. 4 Estimate 5 Answer 5.061 0 9 4 5 - 1 6 3 0 6 . 5 10 1 8.74 3.679 0 -
  25. 25. Now it’s your turn to solve the problems.
  26. 26. Subtract these numbers 8 .4 3 - 2 .7 8 = First line up the decimal points.
  27. 27. Subtract these numbers 3 8 - 5 .6 5 .4 8 .7 7 3 13 13 2
  28. 28. Subtract these numbers 4 .5 - 2 .9 7 = First line up the decimal points.
  29. 29. Subtract these numbers 7 - 3 .5 1 .5 4 .9 3 4 10 14 2 0
  30. 30. Subtract these numbers 1 4 2 .5 – 3 3 .7 1 9 = First line up the decimal points.
  31. 31. Subtract these numbers 7 1 9 - 1 .7 8 5 1 4 2 1 4 10 14 3 3. 0 0 10 9 8 3 11 0 1 .
  32. 32. Problem Solving
  33. 33. Problem Solving Steps What information do you need? What is the problem asking you to find out? Is the answer going to be larger or smaller? What strategies will you use? What operations will you use? How many steps are there and in what order must you do them? How will you solve the problem? Did you check your answer? Does your answer make sense? Analysis Representation Resolution
  34. 34. <ul><li>On the 100-meter dash these children had the following scores: Ivan 13.09, Mary 13.78, Alice 13.8 sec. What was the difference between the highest and lowest times? </li></ul>
  35. 35. Step One <ul><li>Place the numbers in order from greatest to least. </li></ul>13.7 8 13.0 9 13.8 0 13.8 13.7 8 13.0 9
  36. 36. Step Two <ul><li>Subtract the lowest from the highest. </li></ul>9 1 .7 3.8 1 .0 7 10 1 3 0 - sec.
  37. 37. You Deserve a Ribbon!
  38. 38. Copyright Notice <ul><li>This software is copyrighted. The software may not be copied, reproduced, translated or reduced to any electronic medium without the prior written consent of Monica Yuskaitis (monismath@juno.com). However, after you purchase it you may download it in your classroom to use for presentation purposes. </li></ul>
  39. 39. Credits <ul><li>Clipart from clipart.com </li></ul><ul><li>Written by Monica Yuskaitis </li></ul>For Further Information About this product or other Monica’s Math presentations Contact: [email_address]

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