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Decimals

Decimals. What is to be learned?. How to read decimals from a scale. Why Have Decimals?. Difficult to eat a whole mammoth by yourself!. “invented” by?. Abu'l-Hasan al-Uqlidisi . Tenths. 5. 6. 5.1. 5.5. Tenths. 7. 8. 7.3. 7.9. What is to be learned?.

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Decimals

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  1. Decimals

  2. What is to be learned? • How to read decimals from a scale

  3. Why Have Decimals? Difficult to eat a whole mammoth by yourself!

  4. “invented” by? Abu'l-Hasan al-Uqlidisi

  5. Tenths 5 6 5.1 5.5

  6. Tenths 7 8 7.3 7.9

  7. What is to be learned? • How to round to nearest whole number

  8. → 8 to nearest whole number 8.4 8 9 8.4 8.7 8.7 → 9 to nearest whole number

  9. 13.6 → 14 to nearest whole number 13 14 13.6

  10. Without Scales To nearest whole number 3.3 → 3 16.8 → 17 97.4 → 97 46.5 → 47

  11. Tenths 7 8 between 7 and 7.1 7.3 7.9 Hundredths 7 7.1 7.06 7.01

  12. Hundredths 6.4 6.5 6.41 6.49

  13. Estimate Hundredths 2 3 2.19 2.6 2.92 2.60 2.6 is higher than 2.19

  14. Rounding with Hundredths 5.29 → 5 to nearest whole number 5 6 5.81 5.29 5.81 → 6 to nearest whole number

  15. Rounding with Hundredths 9.38 → 9 to nearest whole number 9 10 9.57 9.38 9.57 → 10 to nearest whole number

  16. Without Scales To nearest whole number 7.46 → 7 13.75 → 14 34.29 → 34 101.49 → 101

  17. Finding The Rule to nearest whole number 7 . 2 8 less than 5 → 7 to nearest whole number

  18. Finding The Rule to nearest whole number 6 . 8 1 more than 5 → 7 to nearest whole number always check the first number after the point

  19. Round to Nearest Whole Number Steps to success Look at first number after point less than 5 5 or more 5.2 → 5 → stays the same → go up by one 6.54 → 7

  20. The Test of Success What is to be learned? Steps to success Look at first number after point less than 5 5 or more How to round to nearest whole number → stays the same → go up by one 3.74 13.47 → 4 → 13

  21. What is to be learned? • How to round to 1 decimal place

  22. Measuring All measurements are approximations 34 g

  23. Measuring All measurements are approximations 34.3 g

  24. Measuring All measurements are approximations 34.37 g could go on forever…………………..

  25. Rounding Decimals 4.39 17.4356 usually asked to round to 1 or 2 decimal places 2 decimal places 4 decimal places

  26. Round 2.82 to 1 decimal place between 2.8 and 2.9 Closer to 2.8 2.82 = 2.8 to 1 d.p. 2.8 2.9 2.7 2 2.1 2.2 3 2.3 2.4 2.5 2.6 2.19 2.82 Round 2.19 to 1 decimal place between 2.1 and 2.2 Closer to 2.2 2.19 = 2.2 to 1 d.p.

  27. Without Scales between 6 and 7 6.7 closer to 7 6.7 = 7 to nearest whole number between 2.7 and 2.8 2.73 closer to 2.7 2.73 = 2.7 to 1 decimal place (1 d.p.)

  28. Without Scales between 3.6 and 3.7 3.68 closer to 3.7 3.68 = 3.7 to 1 d. p. between 2.7 and 2.8 2.73 closer to 2.7 2.73 = 2.7 to 1 decimal place (1 d.p.)

  29. Rounding Decimals in Practice 4 8 . 2 to 1 d.p. less than 5 → 8.2 to 1 d.p.

  30. Rounding Decimals in Practice 7 2 . 8 to 1 d.p. over 5 → 2.9 to 1 d.p.

  31. Rounding Decimals in Practice to 1 d.p. 3 . 7 3 less than 5 → 3.7 to 1 d.p.

  32. Rounding Decimals in Practice 2 . 4 2 3 6 9 1 7 6 to 1 d.p. more than 5 → 2.5 to 1 d.p.

  33. Round to 1 Decimal Place Steps to success Leave only one digit after point 2nd digit less than 5 2nd digit 5 or more 2.42 → 2.4 → stays the same → go up by one 6.25 → 6.3

  34. The Test of Success What is to be learned? Steps to success Leave only one digit after point 2nd digit less than 5 2nd digit 5 or more How to round to 1 decimal place → stays the same → go up by one 2.47 9.71 → 2.5 → 9.7

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