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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 412 · 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 67 × 33? (a) 21000 (b) 210 (c) 2100
  2. 2.Best estimate of 16 × 27? (a) 60 (b) 600 (c) 6000
  3. 3.Best estimate of 19 × 74? (a) 1400 (b) 14000 (c) 140
  4. 4.Best estimate of 860 + 764? (a) 1900 (b) 1700 (c) 1500
  5. 5.Best estimate of 58 × 34? (a) 18000 (b) 1800 (c) 180
  6. 6.Best estimate of 77 × 40? (a) 3200 (b) 32000 (c) 320
  7. 7.Best estimate of 58 × 94? (a) 54000 (b) 540 (c) 5400
  8. 8.Best estimate of 52 × 94? (a) 45000 (b) 4500 (c) 450
  9. 9.Best estimate of 280 + 215? (a) 500 (b) 700 (c) 300
  10. 10.Best estimate of 56 × 51? (a) 3000 (b) 30000 (c) 300
  11. 11.Best estimate of 637 + 492? (a) 1300 (b) 1100 (c) 900
  12. 12.Best estimate of 642 + 565? (a) 1000 (b) 1400 (c) 1200
  13. 13.Best estimate of 783 + 804? (a) 1800 (b) 1600 (c) 1400
  14. 14.Best estimate of 80 × 93? (a) 720 (b) 7200 (c) 72000
  15. 15.Best estimate of 97 × 21? (a) 200 (b) 20000 (c) 2000
  16. 16.Best estimate of 259 + 784? (a) 1100 (b) 1300 (c) 900
  17. 17.Best estimate of 70 × 27? (a) 210 (b) 21000 (c) 2100
  18. 18.Best estimate of 615 + 655? (a) 1500 (b) 1300 (c) 1100
  19. 19.Best estimate of 32 × 12? (a) 3000 (b) 300 (c) 30
  20. 20.Best estimate of 420 + 378? (a) 800 (b) 600 (c) 1000
  21. 21.Best estimate of 34 × 41? (a) 1200 (b) 12000 (c) 120
  22. 22.Best estimate of 87 × 61? (a) 540 (b) 54000 (c) 5400
  23. 23.Best estimate of 16 × 92? (a) 18000 (b) 180 (c) 1800
  24. 24.Best estimate of 81 × 83? (a) 64000 (b) 6400 (c) 640
  25. 25.Best estimate of 134 + 461? (a) 400 (b) 600 (c) 800
  26. 26.Best estimate of 58 × 71? (a) 4200 (b) 42000 (c) 420
  27. 27.Best estimate of 504 + 744? (a) 1200 (b) 1400 (c) 1000
  28. 28.Best estimate of 97 × 16? (a) 20000 (b) 2000 (c) 200
  29. 29.Best estimate of 50 × 88? (a) 45000 (b) 4500 (c) 450
  30. 30.Best estimate of 17 × 57? (a) 1200 (b) 120 (c) 12000
  31. 31.Best estimate of 23 × 52? (a) 1000 (b) 10000 (c) 100
  32. 32.Best estimate of 29 × 42? (a) 1200 (b) 120 (c) 12000
  33. 33.Best estimate of 17 × 59? (a) 120 (b) 1200 (c) 12000
  34. 34.Best estimate of 83 × 84? (a) 64000 (b) 640 (c) 6400
  35. 35.Best estimate of 76 × 69? (a) 56000 (b) 560 (c) 5600
  36. 36.Best estimate of 86 × 37? (a) 3600 (b) 360 (c) 36000
  37. 37.Best estimate of 701 + 380? (a) 1100 (b) 1300 (c) 900
  38. 38.Best estimate of 39 × 56? (a) 2400 (b) 240 (c) 24000
  39. 39.Best estimate of 54 × 68? (a) 350 (b) 35000 (c) 3500
  40. 40.Best estimate of 168 + 667? (a) 700 (b) 900 (c) 1100

Answer key

  1. 2100
  2. 600
  3. 1400
  4. 1700
  5. 1800
  6. 3200
  7. 5400
  8. 4500
  9. 500
  10. 3000
  11. 1100
  12. 1200
  13. 1600
  14. 7200
  15. 2000
  16. 1100
  17. 2100
  18. 1300
  19. 300
  20. 800
  21. 1200
  22. 5400
  23. 1800
  24. 6400
  25. 600
  26. 4200
  27. 1200
  28. 2000
  29. 4500
  30. 1200
  31. 1000
  32. 1200
  33. 1200
  34. 6400
  35. 5600
  36. 3600
  37. 1100
  38. 2400
  39. 3500
  40. 900

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