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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 761 · 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 68 × 46? (a) 35000 (b) 350 (c) 3500
  2. 2.Best estimate of 492 + 239? (a) 500 (b) 700 (c) 900
  3. 3.Best estimate of 56 × 73? (a) 42000 (b) 420 (c) 4200
  4. 4.Best estimate of 628 + 597? (a) 1000 (b) 1400 (c) 1200
  5. 5.Best estimate of 360 + 432? (a) 800 (b) 1000 (c) 600
  6. 6.Best estimate of 80 × 59? (a) 4800 (b) 48000 (c) 480
  7. 7.Best estimate of 454 + 516? (a) 1000 (b) 800 (c) 1200
  8. 8.Best estimate of 69 × 91? (a) 6300 (b) 630 (c) 63000
  9. 9.Best estimate of 71 × 60? (a) 4200 (b) 420 (c) 42000
  10. 10.Best estimate of 187 + 749? (a) 1100 (b) 900 (c) 700
  11. 11.Best estimate of 19 × 96? (a) 200 (b) 20000 (c) 2000
  12. 12.Best estimate of 417 + 875? (a) 1300 (b) 1100 (c) 1500
  13. 13.Best estimate of 291 + 441? (a) 700 (b) 500 (c) 900
  14. 14.Best estimate of 291 + 617? (a) 1100 (b) 700 (c) 900
  15. 15.Best estimate of 30 × 13? (a) 30 (b) 300 (c) 3000
  16. 16.Best estimate of 280 + 600? (a) 900 (b) 1100 (c) 700
  17. 17.Best estimate of 90 × 46? (a) 45000 (b) 450 (c) 4500
  18. 18.Best estimate of 63 × 46? (a) 30000 (b) 300 (c) 3000
  19. 19.Best estimate of 165 + 865? (a) 1300 (b) 1100 (c) 900
  20. 20.Best estimate of 715 + 340? (a) 1200 (b) 800 (c) 1000
  21. 21.Best estimate of 88 × 86? (a) 8100 (b) 810 (c) 81000
  22. 22.Best estimate of 357 + 714? (a) 1300 (b) 1100 (c) 900
  23. 23.Best estimate of 570 + 257? (a) 1100 (b) 900 (c) 700
  24. 24.Best estimate of 365 + 717? (a) 1100 (b) 1300 (c) 900
  25. 25.Best estimate of 81 × 17? (a) 1600 (b) 160 (c) 16000
  26. 26.Best estimate of 217 + 811? (a) 800 (b) 1200 (c) 1000
  27. 27.Best estimate of 40 × 66? (a) 28000 (b) 2800 (c) 280
  28. 28.Best estimate of 27 × 96? (a) 3000 (b) 30000 (c) 300
  29. 29.Best estimate of 26 × 72? (a) 210 (b) 2100 (c) 21000
  30. 30.Best estimate of 340 + 275? (a) 400 (b) 800 (c) 600
  31. 31.Best estimate of 166 + 689? (a) 1100 (b) 900 (c) 700
  32. 32.Best estimate of 16 × 36? (a) 80 (b) 800 (c) 8000
  33. 33.Best estimate of 42 × 26? (a) 1200 (b) 120 (c) 12000
  34. 34.Best estimate of 96 × 91? (a) 9000 (b) 90000 (c) 900
  35. 35.Best estimate of 13 × 93? (a) 9000 (b) 90 (c) 900
  36. 36.Best estimate of 31 × 37? (a) 12000 (b) 1200 (c) 120
  37. 37.Best estimate of 473 + 863? (a) 1400 (b) 1200 (c) 1600
  38. 38.Best estimate of 14 × 72? (a) 700 (b) 70 (c) 7000
  39. 39.Best estimate of 548 + 320? (a) 600 (b) 1000 (c) 800
  40. 40.Best estimate of 284 + 294? (a) 800 (b) 600 (c) 400

Answer key

  1. 3500
  2. 700
  3. 4200
  4. 1200
  5. 800
  6. 4800
  7. 1000
  8. 6300
  9. 4200
  10. 900
  11. 2000
  12. 1300
  13. 700
  14. 900
  15. 300
  16. 900
  17. 4500
  18. 3000
  19. 1100
  20. 1000
  21. 8100
  22. 1100
  23. 900
  24. 1100
  25. 1600
  26. 1000
  27. 2800
  28. 3000
  29. 2100
  30. 600
  31. 900
  32. 800
  33. 1200
  34. 9000
  35. 900
  36. 1200
  37. 1400
  38. 700
  39. 800
  40. 600

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