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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 458 · 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 96 × 66? (a) 7000 (b) 700 (c) 70000
  2. 2.Best estimate of 87 × 63? (a) 54000 (b) 5400 (c) 540
  3. 3.Best estimate of 70 × 40? (a) 2800 (b) 28000 (c) 280
  4. 4.Best estimate of 89 × 74? (a) 630 (b) 63000 (c) 6300
  5. 5.Best estimate of 261 + 570? (a) 1100 (b) 900 (c) 700
  6. 6.Best estimate of 67 × 96? (a) 7000 (b) 70000 (c) 700
  7. 7.Best estimate of 429 + 165? (a) 400 (b) 800 (c) 600
  8. 8.Best estimate of 39 × 78? (a) 32000 (b) 320 (c) 3200
  9. 9.Best estimate of 632 + 868? (a) 1700 (b) 1300 (c) 1500
  10. 10.Best estimate of 62 × 63? (a) 36000 (b) 360 (c) 3600
  11. 11.Best estimate of 442 + 418? (a) 800 (b) 1000 (c) 600
  12. 12.Best estimate of 824 + 575? (a) 1600 (b) 1200 (c) 1400
  13. 13.Best estimate of 59 × 27? (a) 1800 (b) 180 (c) 18000
  14. 14.Best estimate of 733 + 347? (a) 1000 (b) 1200 (c) 800
  15. 15.Best estimate of 61 × 92? (a) 540 (b) 5400 (c) 54000
  16. 16.Best estimate of 281 + 665? (a) 1200 (b) 800 (c) 1000
  17. 17.Best estimate of 451 + 200? (a) 700 (b) 900 (c) 500
  18. 18.Best estimate of 585 + 684? (a) 1500 (b) 1300 (c) 1100
  19. 19.Best estimate of 842 + 125? (a) 700 (b) 900 (c) 1100
  20. 20.Best estimate of 70 × 22? (a) 1400 (b) 14000 (c) 140
  21. 21.Best estimate of 298 + 221? (a) 300 (b) 500 (c) 700
  22. 22.Best estimate of 30 × 36? (a) 12000 (b) 120 (c) 1200
  23. 23.Best estimate of 711 + 839? (a) 1300 (b) 1700 (c) 1500
  24. 24.Best estimate of 177 + 563? (a) 800 (b) 1000 (c) 600
  25. 25.Best estimate of 817 + 479? (a) 1500 (b) 1100 (c) 1300
  26. 26.Best estimate of 178 + 599? (a) 1000 (b) 800 (c) 600
  27. 27.Best estimate of 86 × 87? (a) 81000 (b) 810 (c) 8100
  28. 28.Best estimate of 39 × 50? (a) 200 (b) 20000 (c) 2000
  29. 29.Best estimate of 722 + 629? (a) 1500 (b) 1100 (c) 1300
  30. 30.Best estimate of 335 + 613? (a) 1100 (b) 700 (c) 900
  31. 31.Best estimate of 238 + 866? (a) 1100 (b) 1300 (c) 900
  32. 32.Best estimate of 23 × 37? (a) 8000 (b) 800 (c) 80
  33. 33.Best estimate of 97 × 29? (a) 300 (b) 3000 (c) 30000
  34. 34.Best estimate of 851 + 143? (a) 1200 (b) 800 (c) 1000
  35. 35.Best estimate of 68 × 34? (a) 2100 (b) 210 (c) 21000
  36. 36.Best estimate of 462 + 342? (a) 600 (b) 1000 (c) 800
  37. 37.Best estimate of 503 + 589? (a) 900 (b) 1100 (c) 1300
  38. 38.Best estimate of 26 × 91? (a) 270 (b) 27000 (c) 2700
  39. 39.Best estimate of 16 × 69? (a) 1400 (b) 140 (c) 14000
  40. 40.Best estimate of 74 × 68? (a) 4900 (b) 49000 (c) 490

Answer key

  1. 7000
  2. 5400
  3. 2800
  4. 6300
  5. 900
  6. 7000
  7. 600
  8. 3200
  9. 1500
  10. 3600
  11. 800
  12. 1400
  13. 1800
  14. 1000
  15. 5400
  16. 1000
  17. 700
  18. 1300
  19. 900
  20. 1400
  21. 500
  22. 1200
  23. 1500
  24. 800
  25. 1300
  26. 800
  27. 8100
  28. 2000
  29. 1300
  30. 900
  31. 1100
  32. 800
  33. 3000
  34. 1000
  35. 2100
  36. 800
  37. 1100
  38. 2700
  39. 1400
  40. 4900

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