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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 160 · 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 32 × 21? (a) 600 (b) 60 (c) 6000
  2. 2.Best estimate of 29 × 78? (a) 24000 (b) 240 (c) 2400
  3. 3.Best estimate of 50 × 60? (a) 300 (b) 30000 (c) 3000
  4. 4.Best estimate of 681 + 767? (a) 1700 (b) 1500 (c) 1300
  5. 5.Best estimate of 83 × 72? (a) 56000 (b) 560 (c) 5600
  6. 6.Best estimate of 370 + 269? (a) 700 (b) 500 (c) 900
  7. 7.Best estimate of 39 × 73? (a) 280 (b) 2800 (c) 28000
  8. 8.Best estimate of 91 × 16? (a) 1800 (b) 18000 (c) 180
  9. 9.Best estimate of 795 + 807? (a) 1600 (b) 1400 (c) 1800
  10. 10.Best estimate of 14 × 64? (a) 6000 (b) 60 (c) 600
  11. 11.Best estimate of 97 × 32? (a) 30000 (b) 3000 (c) 300
  12. 12.Best estimate of 31 × 91? (a) 2700 (b) 270 (c) 27000
  13. 13.Best estimate of 525 + 160? (a) 700 (b) 500 (c) 900
  14. 14.Best estimate of 632 + 753? (a) 1600 (b) 1400 (c) 1200
  15. 15.Best estimate of 54 × 76? (a) 400 (b) 40000 (c) 4000
  16. 16.Best estimate of 59 × 92? (a) 54000 (b) 5400 (c) 540
  17. 17.Best estimate of 98 × 79? (a) 800 (b) 8000 (c) 80000
  18. 18.Best estimate of 94 × 42? (a) 36000 (b) 360 (c) 3600
  19. 19.Best estimate of 195 + 532? (a) 700 (b) 900 (c) 500
  20. 20.Best estimate of 763 + 236? (a) 1200 (b) 1000 (c) 800
  21. 21.Best estimate of 22 × 28? (a) 60 (b) 6000 (c) 600
  22. 22.Best estimate of 510 + 584? (a) 1100 (b) 900 (c) 1300
  23. 23.Best estimate of 629 + 204? (a) 1000 (b) 600 (c) 800
  24. 24.Best estimate of 76 × 66? (a) 560 (b) 56000 (c) 5600
  25. 25.Best estimate of 36 × 36? (a) 1600 (b) 16000 (c) 160
  26. 26.Best estimate of 28 × 37? (a) 1200 (b) 12000 (c) 120
  27. 27.Best estimate of 73 × 20? (a) 1400 (b) 14000 (c) 140
  28. 28.Best estimate of 86 × 79? (a) 7200 (b) 720 (c) 72000
  29. 29.Best estimate of 637 + 791? (a) 1400 (b) 1200 (c) 1600
  30. 30.Best estimate of 39 × 81? (a) 320 (b) 3200 (c) 32000
  31. 31.Best estimate of 404 + 164? (a) 800 (b) 600 (c) 400
  32. 32.Best estimate of 92 × 30? (a) 270 (b) 2700 (c) 27000
  33. 33.Best estimate of 12 × 87? (a) 90 (b) 9000 (c) 900
  34. 34.Best estimate of 66 × 72? (a) 49000 (b) 490 (c) 4900
  35. 35.Best estimate of 86 × 70? (a) 630 (b) 63000 (c) 6300
  36. 36.Best estimate of 166 + 234? (a) 600 (b) 200 (c) 400
  37. 37.Best estimate of 126 + 537? (a) 400 (b) 800 (c) 600
  38. 38.Best estimate of 585 + 169? (a) 1000 (b) 600 (c) 800
  39. 39.Best estimate of 76 × 72? (a) 56000 (b) 560 (c) 5600
  40. 40.Best estimate of 320 + 484? (a) 600 (b) 1000 (c) 800

Answer key

  1. 600
  2. 2400
  3. 3000
  4. 1500
  5. 5600
  6. 700
  7. 2800
  8. 1800
  9. 1600
  10. 600
  11. 3000
  12. 2700
  13. 700
  14. 1400
  15. 4000
  16. 5400
  17. 8000
  18. 3600
  19. 700
  20. 1000
  21. 600
  22. 1100
  23. 800
  24. 5600
  25. 1600
  26. 1200
  27. 1400
  28. 7200
  29. 1400
  30. 3200
  31. 600
  32. 2700
  33. 900
  34. 4900
  35. 6300
  36. 400
  37. 600
  38. 800
  39. 5600
  40. 800

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