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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 607 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 90 × 76? (a) 72000 (b) 7200 (c) 720
  2. 2.Best estimate of 676 + 531? (a) 1200 (b) 1000 (c) 1400
  3. 3.Best estimate of 437 + 542? (a) 900 (b) 700 (c) 1100
  4. 4.Best estimate of 12 × 78? (a) 80 (b) 800 (c) 8000
  5. 5.Best estimate of 89 × 71? (a) 63000 (b) 6300 (c) 630
  6. 6.Best estimate of 47 × 22? (a) 10000 (b) 100 (c) 1000
  7. 7.Best estimate of 64 × 20? (a) 12000 (b) 1200 (c) 120
  8. 8.Best estimate of 19 × 66? (a) 1400 (b) 14000 (c) 140
  9. 9.Best estimate of 361 + 462? (a) 1100 (b) 700 (c) 900
  10. 10.Best estimate of 97 × 93? (a) 9000 (b) 90000 (c) 900
  11. 11.Best estimate of 156 + 496? (a) 500 (b) 700 (c) 900
  12. 12.Best estimate of 66 × 79? (a) 560 (b) 5600 (c) 56000
  13. 13.Best estimate of 71 × 84? (a) 560 (b) 56000 (c) 5600
  14. 14.Best estimate of 38 × 37? (a) 16000 (b) 160 (c) 1600
  15. 15.Best estimate of 79 × 60? (a) 4800 (b) 48000 (c) 480
  16. 16.Best estimate of 852 + 846? (a) 1500 (b) 1700 (c) 1900
  17. 17.Best estimate of 186 + 339? (a) 700 (b) 300 (c) 500
  18. 18.Best estimate of 191 + 565? (a) 1000 (b) 800 (c) 600
  19. 19.Best estimate of 13 × 60? (a) 6000 (b) 60 (c) 600
  20. 20.Best estimate of 542 + 855? (a) 1400 (b) 1200 (c) 1600
  21. 21.Best estimate of 63 × 97? (a) 6000 (b) 60000 (c) 600
  22. 22.Best estimate of 564 + 751? (a) 1400 (b) 1600 (c) 1200
  23. 23.Best estimate of 620 + 120? (a) 700 (b) 900 (c) 500
  24. 24.Best estimate of 31 × 79? (a) 240 (b) 24000 (c) 2400
  25. 25.Best estimate of 79 × 74? (a) 56000 (b) 5600 (c) 560
  26. 26.Best estimate of 718 + 812? (a) 1300 (b) 1700 (c) 1500
  27. 27.Best estimate of 22 × 59? (a) 1200 (b) 120 (c) 12000
  28. 28.Best estimate of 47 × 24? (a) 100 (b) 1000 (c) 10000
  29. 29.Best estimate of 31 × 34? (a) 90 (b) 900 (c) 9000
  30. 30.Best estimate of 46 × 58? (a) 30000 (b) 3000 (c) 300
  31. 31.Best estimate of 27 × 72? (a) 2100 (b) 210 (c) 21000
  32. 32.Best estimate of 96 × 14? (a) 100 (b) 10000 (c) 1000
  33. 33.Best estimate of 86 × 42? (a) 36000 (b) 360 (c) 3600
  34. 34.Best estimate of 248 + 712? (a) 900 (b) 1100 (c) 700
  35. 35.Best estimate of 26 × 84? (a) 24000 (b) 240 (c) 2400
  36. 36.Best estimate of 148 + 627? (a) 700 (b) 500 (c) 900
  37. 37.Best estimate of 98 × 87? (a) 90000 (b) 9000 (c) 900
  38. 38.Best estimate of 126 + 628? (a) 700 (b) 500 (c) 900
  39. 39.Best estimate of 54 × 57? (a) 3000 (b) 30000 (c) 300
  40. 40.Best estimate of 129 + 126? (a) 0 (b) 200 (c) 400

Answer key

  1. 7200
  2. 1200
  3. 900
  4. 800
  5. 6300
  6. 1000
  7. 1200
  8. 1400
  9. 900
  10. 9000
  11. 700
  12. 5600
  13. 5600
  14. 1600
  15. 4800
  16. 1700
  17. 500
  18. 800
  19. 600
  20. 1400
  21. 6000
  22. 1400
  23. 700
  24. 2400
  25. 5600
  26. 1500
  27. 1200
  28. 1000
  29. 900
  30. 3000
  31. 2100
  32. 1000
  33. 3600
  34. 900
  35. 2400
  36. 700
  37. 9000
  38. 700
  39. 3000
  40. 200

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