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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 4 · 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 58 × 92? (a) 54000 (b) 540 (c) 5400
  2. 2.Best estimate of 869 + 514? (a) 1200 (b) 1400 (c) 1600
  3. 3.Best estimate of 651 + 505? (a) 1200 (b) 1400 (c) 1000
  4. 4.Best estimate of 88 × 91? (a) 8100 (b) 81000 (c) 810
  5. 5.Best estimate of 26 × 84? (a) 2400 (b) 240 (c) 24000
  6. 6.Best estimate of 74 × 17? (a) 1400 (b) 140 (c) 14000
  7. 7.Best estimate of 32 × 13? (a) 300 (b) 30 (c) 3000
  8. 8.Best estimate of 29 × 19? (a) 6000 (b) 60 (c) 600
  9. 9.Best estimate of 37 × 74? (a) 28000 (b) 2800 (c) 280
  10. 10.Best estimate of 349 + 195? (a) 500 (b) 700 (c) 300
  11. 11.Best estimate of 791 + 192? (a) 800 (b) 1000 (c) 1200
  12. 12.Best estimate of 366 + 174? (a) 600 (b) 400 (c) 800
  13. 13.Best estimate of 51 × 31? (a) 150 (b) 1500 (c) 15000
  14. 14.Best estimate of 29 × 63? (a) 1800 (b) 180 (c) 18000
  15. 15.Best estimate of 49 × 67? (a) 35000 (b) 350 (c) 3500
  16. 16.Best estimate of 81 × 91? (a) 720 (b) 7200 (c) 72000
  17. 17.Best estimate of 72 × 41? (a) 28000 (b) 280 (c) 2800
  18. 18.Best estimate of 47 × 43? (a) 200 (b) 20000 (c) 2000
  19. 19.Best estimate of 26 × 40? (a) 1200 (b) 120 (c) 12000
  20. 20.Best estimate of 76 × 86? (a) 720 (b) 7200 (c) 72000
  21. 21.Best estimate of 59 × 28? (a) 180 (b) 18000 (c) 1800
  22. 22.Best estimate of 811 + 306? (a) 1300 (b) 1100 (c) 900
  23. 23.Best estimate of 54 × 16? (a) 10000 (b) 1000 (c) 100
  24. 24.Best estimate of 18 × 63? (a) 1200 (b) 12000 (c) 120
  25. 25.Best estimate of 83 × 63? (a) 480 (b) 4800 (c) 48000
  26. 26.Best estimate of 682 + 365? (a) 1100 (b) 1300 (c) 900
  27. 27.Best estimate of 825 + 265? (a) 900 (b) 1100 (c) 1300
  28. 28.Best estimate of 63 × 27? (a) 1800 (b) 180 (c) 18000
  29. 29.Best estimate of 83 × 56? (a) 480 (b) 4800 (c) 48000
  30. 30.Best estimate of 59 × 36? (a) 24000 (b) 240 (c) 2400
  31. 31.Best estimate of 355 + 433? (a) 1000 (b) 800 (c) 600
  32. 32.Best estimate of 46 × 98? (a) 50000 (b) 500 (c) 5000
  33. 33.Best estimate of 284 + 173? (a) 500 (b) 700 (c) 300
  34. 34.Best estimate of 807 + 443? (a) 1400 (b) 1200 (c) 1000
  35. 35.Best estimate of 137 + 352? (a) 700 (b) 500 (c) 300
  36. 36.Best estimate of 532 + 752? (a) 1100 (b) 1300 (c) 1500
  37. 37.Best estimate of 12 × 17? (a) 2000 (b) 200 (c) 20
  38. 38.Best estimate of 41 × 66? (a) 280 (b) 2800 (c) 28000
  39. 39.Best estimate of 876 + 447? (a) 1300 (b) 1100 (c) 1500
  40. 40.Best estimate of 457 + 637? (a) 1100 (b) 900 (c) 1300

Answer key

  1. 5400
  2. 1400
  3. 1200
  4. 8100
  5. 2400
  6. 1400
  7. 300
  8. 600
  9. 2800
  10. 500
  11. 1000
  12. 600
  13. 1500
  14. 1800
  15. 3500
  16. 7200
  17. 2800
  18. 2000
  19. 1200
  20. 7200
  21. 1800
  22. 1100
  23. 1000
  24. 1200
  25. 4800
  26. 1100
  27. 1100
  28. 1800
  29. 4800
  30. 2400
  31. 800
  32. 5000
  33. 500
  34. 1200
  35. 500
  36. 1300
  37. 200
  38. 2800
  39. 1300
  40. 1100

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