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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 211 · 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 342 + 621? (a) 1100 (b) 900 (c) 700
  2. 2.Best estimate of 19 × 79? (a) 160 (b) 1600 (c) 16000
  3. 3.Best estimate of 90 × 67? (a) 6300 (b) 630 (c) 63000
  4. 4.Best estimate of 242 + 189? (a) 600 (b) 400 (c) 200
  5. 5.Best estimate of 71 × 61? (a) 42000 (b) 420 (c) 4200
  6. 6.Best estimate of 86 × 79? (a) 720 (b) 72000 (c) 7200
  7. 7.Best estimate of 741 + 559? (a) 1500 (b) 1300 (c) 1100
  8. 8.Best estimate of 43 × 26? (a) 1200 (b) 12000 (c) 120
  9. 9.Best estimate of 57 × 30? (a) 180 (b) 18000 (c) 1800
  10. 10.Best estimate of 17 × 27? (a) 60 (b) 6000 (c) 600
  11. 11.Best estimate of 29 × 16? (a) 60 (b) 600 (c) 6000
  12. 12.Best estimate of 13 × 12? (a) 100 (b) 1000 (c) 10
  13. 13.Best estimate of 273 + 437? (a) 900 (b) 500 (c) 700
  14. 14.Best estimate of 71 × 82? (a) 560 (b) 5600 (c) 56000
  15. 15.Best estimate of 94 × 12? (a) 9000 (b) 900 (c) 90
  16. 16.Best estimate of 143 + 190? (a) 100 (b) 300 (c) 500
  17. 17.Best estimate of 87 × 33? (a) 2700 (b) 27000 (c) 270
  18. 18.Best estimate of 44 × 82? (a) 3200 (b) 32000 (c) 320
  19. 19.Best estimate of 28 × 98? (a) 3000 (b) 30000 (c) 300
  20. 20.Best estimate of 292 + 357? (a) 900 (b) 500 (c) 700
  21. 21.Best estimate of 77 × 12? (a) 80 (b) 800 (c) 8000
  22. 22.Best estimate of 14 × 97? (a) 1000 (b) 100 (c) 10000
  23. 23.Best estimate of 39 × 42? (a) 1600 (b) 16000 (c) 160
  24. 24.Best estimate of 444 + 269? (a) 700 (b) 900 (c) 500
  25. 25.Best estimate of 714 + 586? (a) 1500 (b) 1300 (c) 1100
  26. 26.Best estimate of 79 × 43? (a) 320 (b) 32000 (c) 3200
  27. 27.Best estimate of 27 × 96? (a) 30000 (b) 300 (c) 3000
  28. 28.Best estimate of 627 + 564? (a) 1200 (b) 1000 (c) 1400
  29. 29.Best estimate of 86 × 21? (a) 18000 (b) 180 (c) 1800
  30. 30.Best estimate of 140 + 127? (a) 200 (b) 400 (c) 0
  31. 31.Best estimate of 58 × 86? (a) 5400 (b) 540 (c) 54000
  32. 32.Best estimate of 366 + 779? (a) 1200 (b) 1400 (c) 1000
  33. 33.Best estimate of 659 + 530? (a) 1400 (b) 1200 (c) 1000
  34. 34.Best estimate of 84 × 73? (a) 56000 (b) 5600 (c) 560
  35. 35.Best estimate of 196 + 786? (a) 1000 (b) 1200 (c) 800
  36. 36.Best estimate of 81 × 27? (a) 2400 (b) 240 (c) 24000
  37. 37.Best estimate of 531 + 705? (a) 1000 (b) 1200 (c) 1400
  38. 38.Best estimate of 36 × 28? (a) 1200 (b) 12000 (c) 120
  39. 39.Best estimate of 80 × 62? (a) 4800 (b) 48000 (c) 480
  40. 40.Best estimate of 91 × 34? (a) 27000 (b) 270 (c) 2700

Answer key

  1. 900
  2. 1600
  3. 6300
  4. 400
  5. 4200
  6. 7200
  7. 1300
  8. 1200
  9. 1800
  10. 600
  11. 600
  12. 100
  13. 700
  14. 5600
  15. 900
  16. 300
  17. 2700
  18. 3200
  19. 3000
  20. 700
  21. 800
  22. 1000
  23. 1600
  24. 700
  25. 1300
  26. 3200
  27. 3000
  28. 1200
  29. 1800
  30. 200
  31. 5400
  32. 1200
  33. 1200
  34. 5600
  35. 1000
  36. 2400
  37. 1200
  38. 1200
  39. 4800
  40. 2700

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