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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 57 · 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 72 × 88? (a) 6300 (b) 630 (c) 63000
  2. 2.Best estimate of 29 × 62? (a) 1800 (b) 180 (c) 18000
  3. 3.Best estimate of 518 + 419? (a) 700 (b) 900 (c) 1100
  4. 4.Best estimate of 61 × 71? (a) 420 (b) 42000 (c) 4200
  5. 5.Best estimate of 32 × 83? (a) 240 (b) 24000 (c) 2400
  6. 6.Best estimate of 44 × 79? (a) 3200 (b) 32000 (c) 320
  7. 7.Best estimate of 840 + 481? (a) 1500 (b) 1300 (c) 1100
  8. 8.Best estimate of 825 + 172? (a) 1000 (b) 1200 (c) 800
  9. 9.Best estimate of 52 × 82? (a) 40000 (b) 400 (c) 4000
  10. 10.Best estimate of 92 × 18? (a) 18000 (b) 180 (c) 1800
  11. 11.Best estimate of 66 × 93? (a) 6300 (b) 630 (c) 63000
  12. 12.Best estimate of 786 + 179? (a) 800 (b) 1200 (c) 1000
  13. 13.Best estimate of 183 + 553? (a) 1000 (b) 800 (c) 600
  14. 14.Best estimate of 59 × 47? (a) 300 (b) 3000 (c) 30000
  15. 15.Best estimate of 46 × 37? (a) 2000 (b) 20000 (c) 200
  16. 16.Best estimate of 855 + 410? (a) 1500 (b) 1100 (c) 1300
  17. 17.Best estimate of 240 + 641? (a) 800 (b) 600 (c) 1000
  18. 18.Best estimate of 38 × 64? (a) 2400 (b) 24000 (c) 240
  19. 19.Best estimate of 752 + 780? (a) 1800 (b) 1400 (c) 1600
  20. 20.Best estimate of 88 × 56? (a) 54000 (b) 5400 (c) 540
  21. 21.Best estimate of 228 + 695? (a) 1100 (b) 700 (c) 900
  22. 22.Best estimate of 185 + 488? (a) 500 (b) 900 (c) 700
  23. 23.Best estimate of 51 × 17? (a) 100 (b) 10000 (c) 1000
  24. 24.Best estimate of 326 + 358? (a) 900 (b) 700 (c) 500
  25. 25.Best estimate of 538 + 671? (a) 1400 (b) 1000 (c) 1200
  26. 26.Best estimate of 536 + 601? (a) 1100 (b) 1300 (c) 900
  27. 27.Best estimate of 148 + 351? (a) 500 (b) 700 (c) 300
  28. 28.Best estimate of 70 × 86? (a) 6300 (b) 63000 (c) 630
  29. 29.Best estimate of 300 + 532? (a) 1000 (b) 600 (c) 800
  30. 30.Best estimate of 67 × 96? (a) 70000 (b) 700 (c) 7000
  31. 31.Best estimate of 80 × 28? (a) 240 (b) 24000 (c) 2400
  32. 32.Best estimate of 124 + 578? (a) 500 (b) 700 (c) 900
  33. 33.Best estimate of 334 + 827? (a) 1100 (b) 1300 (c) 900
  34. 34.Best estimate of 47 × 46? (a) 250 (b) 2500 (c) 25000
  35. 35.Best estimate of 663 + 652? (a) 1400 (b) 1600 (c) 1200
  36. 36.Best estimate of 22 × 33? (a) 600 (b) 60 (c) 6000
  37. 37.Best estimate of 474 + 638? (a) 900 (b) 1100 (c) 1300
  38. 38.Best estimate of 67 × 40? (a) 28000 (b) 280 (c) 2800
  39. 39.Best estimate of 240 + 424? (a) 800 (b) 600 (c) 400
  40. 40.Best estimate of 20 × 57? (a) 120 (b) 12000 (c) 1200

Answer key

  1. 6300
  2. 1800
  3. 900
  4. 4200
  5. 2400
  6. 3200
  7. 1300
  8. 1000
  9. 4000
  10. 1800
  11. 6300
  12. 1000
  13. 800
  14. 3000
  15. 2000
  16. 1300
  17. 800
  18. 2400
  19. 1600
  20. 5400
  21. 900
  22. 700
  23. 1000
  24. 700
  25. 1200
  26. 1100
  27. 500
  28. 6300
  29. 800
  30. 7000
  31. 2400
  32. 700
  33. 1100
  34. 2500
  35. 1400
  36. 600
  37. 1100
  38. 2800
  39. 600
  40. 1200

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