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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 593 · 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 20 × 77? (a) 160 (b) 16000 (c) 1600
  2. 2.Best estimate of 42 × 17? (a) 8000 (b) 80 (c) 800
  3. 3.Best estimate of 44 × 62? (a) 24000 (b) 240 (c) 2400
  4. 4.Best estimate of 416 + 558? (a) 1000 (b) 800 (c) 1200
  5. 5.Best estimate of 623 + 466? (a) 1100 (b) 1300 (c) 900
  6. 6.Best estimate of 654 + 801? (a) 1300 (b) 1500 (c) 1700
  7. 7.Best estimate of 40 × 32? (a) 1200 (b) 120 (c) 12000
  8. 8.Best estimate of 327 + 334? (a) 600 (b) 800 (c) 400
  9. 9.Best estimate of 88 × 93? (a) 81000 (b) 810 (c) 8100
  10. 10.Best estimate of 64 × 36? (a) 2400 (b) 24000 (c) 240
  11. 11.Best estimate of 536 + 798? (a) 1500 (b) 1100 (c) 1300
  12. 12.Best estimate of 851 + 513? (a) 1600 (b) 1200 (c) 1400
  13. 13.Best estimate of 169 + 764? (a) 1200 (b) 1000 (c) 800
  14. 14.Best estimate of 762 + 336? (a) 1300 (b) 1100 (c) 900
  15. 15.Best estimate of 293 + 205? (a) 500 (b) 700 (c) 300
  16. 16.Best estimate of 40 × 59? (a) 2400 (b) 24000 (c) 240
  17. 17.Best estimate of 313 + 220? (a) 700 (b) 500 (c) 300
  18. 18.Best estimate of 68 × 87? (a) 630 (b) 6300 (c) 63000
  19. 19.Best estimate of 875 + 395? (a) 1300 (b) 1500 (c) 1100
  20. 20.Best estimate of 54 × 18? (a) 10000 (b) 100 (c) 1000
  21. 21.Best estimate of 20 × 58? (a) 120 (b) 12000 (c) 1200
  22. 22.Best estimate of 86 × 87? (a) 8100 (b) 81000 (c) 810
  23. 23.Best estimate of 191 + 795? (a) 800 (b) 1200 (c) 1000
  24. 24.Best estimate of 16 × 19? (a) 4000 (b) 40 (c) 400
  25. 25.Best estimate of 855 + 649? (a) 1700 (b) 1500 (c) 1300
  26. 26.Best estimate of 52 × 24? (a) 10000 (b) 1000 (c) 100
  27. 27.Best estimate of 648 + 148? (a) 900 (b) 500 (c) 700
  28. 28.Best estimate of 257 + 265? (a) 600 (b) 800 (c) 400
  29. 29.Best estimate of 52 × 66? (a) 35000 (b) 350 (c) 3500
  30. 30.Best estimate of 23 × 36? (a) 800 (b) 8000 (c) 80
  31. 31.Best estimate of 321 + 208? (a) 300 (b) 500 (c) 700
  32. 32.Best estimate of 68 × 43? (a) 280 (b) 2800 (c) 28000
  33. 33.Best estimate of 282 + 121? (a) 600 (b) 200 (c) 400
  34. 34.Best estimate of 670 + 156? (a) 700 (b) 1100 (c) 900
  35. 35.Best estimate of 26 × 16? (a) 600 (b) 6000 (c) 60
  36. 36.Best estimate of 398 + 709? (a) 1300 (b) 900 (c) 1100
  37. 37.Best estimate of 174 + 193? (a) 200 (b) 400 (c) 600
  38. 38.Best estimate of 491 + 603? (a) 900 (b) 1100 (c) 1300
  39. 39.Best estimate of 575 + 164? (a) 600 (b) 800 (c) 1000
  40. 40.Best estimate of 584 + 300? (a) 1100 (b) 700 (c) 900

Answer key

  1. 1600
  2. 800
  3. 2400
  4. 1000
  5. 1100
  6. 1500
  7. 1200
  8. 600
  9. 8100
  10. 2400
  11. 1300
  12. 1400
  13. 1000
  14. 1100
  15. 500
  16. 2400
  17. 500
  18. 6300
  19. 1300
  20. 1000
  21. 1200
  22. 8100
  23. 1000
  24. 400
  25. 1500
  26. 1000
  27. 700
  28. 600
  29. 3500
  30. 800
  31. 500
  32. 2800
  33. 400
  34. 900
  35. 600
  36. 1100
  37. 400
  38. 1100
  39. 800
  40. 900

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