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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 875 · 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 36 × 90? (a) 360 (b) 36000 (c) 3600
  2. 2.Best estimate of 618 + 334? (a) 1100 (b) 700 (c) 900
  3. 3.Best estimate of 334 + 522? (a) 800 (b) 1000 (c) 600
  4. 4.Best estimate of 31 × 77? (a) 240 (b) 2400 (c) 24000
  5. 5.Best estimate of 88 × 50? (a) 450 (b) 45000 (c) 4500
  6. 6.Best estimate of 672 + 199? (a) 900 (b) 1100 (c) 700
  7. 7.Best estimate of 157 + 718? (a) 900 (b) 1100 (c) 700
  8. 8.Best estimate of 645 + 203? (a) 600 (b) 1000 (c) 800
  9. 9.Best estimate of 390 + 496? (a) 900 (b) 700 (c) 1100
  10. 10.Best estimate of 508 + 168? (a) 500 (b) 700 (c) 900
  11. 11.Best estimate of 12 × 58? (a) 600 (b) 6000 (c) 60
  12. 12.Best estimate of 29 × 80? (a) 2400 (b) 240 (c) 24000
  13. 13.Best estimate of 18 × 18? (a) 40 (b) 4000 (c) 400
  14. 14.Best estimate of 88 × 93? (a) 81000 (b) 8100 (c) 810
  15. 15.Best estimate of 204 + 800? (a) 1000 (b) 1200 (c) 800
  16. 16.Best estimate of 31 × 37? (a) 120 (b) 1200 (c) 12000
  17. 17.Best estimate of 93 × 32? (a) 270 (b) 27000 (c) 2700
  18. 18.Best estimate of 36 × 38? (a) 160 (b) 16000 (c) 1600
  19. 19.Best estimate of 68 × 86? (a) 63000 (b) 6300 (c) 630
  20. 20.Best estimate of 89 × 29? (a) 27000 (b) 2700 (c) 270
  21. 21.Best estimate of 81 × 20? (a) 16000 (b) 1600 (c) 160
  22. 22.Best estimate of 456 + 190? (a) 900 (b) 700 (c) 500
  23. 23.Best estimate of 816 + 506? (a) 1300 (b) 1100 (c) 1500
  24. 24.Best estimate of 29 × 77? (a) 240 (b) 2400 (c) 24000
  25. 25.Best estimate of 28 × 56? (a) 1800 (b) 18000 (c) 180
  26. 26.Best estimate of 36 × 78? (a) 32000 (b) 320 (c) 3200
  27. 27.Best estimate of 98 × 90? (a) 90000 (b) 9000 (c) 900
  28. 28.Best estimate of 18 × 87? (a) 18000 (b) 180 (c) 1800
  29. 29.Best estimate of 67 × 44? (a) 2800 (b) 280 (c) 28000
  30. 30.Best estimate of 594 + 326? (a) 700 (b) 900 (c) 1100
  31. 31.Best estimate of 185 + 778? (a) 1000 (b) 1200 (c) 800
  32. 32.Best estimate of 51 × 27? (a) 1500 (b) 15000 (c) 150
  33. 33.Best estimate of 429 + 480? (a) 700 (b) 900 (c) 1100
  34. 34.Best estimate of 52 × 46? (a) 25000 (b) 2500 (c) 250
  35. 35.Best estimate of 476 + 756? (a) 1300 (b) 1500 (c) 1100
  36. 36.Best estimate of 409 + 483? (a) 700 (b) 1100 (c) 900
  37. 37.Best estimate of 467 + 134? (a) 800 (b) 400 (c) 600
  38. 38.Best estimate of 76 × 96? (a) 80000 (b) 8000 (c) 800
  39. 39.Best estimate of 220 + 356? (a) 400 (b) 600 (c) 800
  40. 40.Best estimate of 368 + 535? (a) 1100 (b) 900 (c) 700

Answer key

  1. 3600
  2. 900
  3. 800
  4. 2400
  5. 4500
  6. 900
  7. 900
  8. 800
  9. 900
  10. 700
  11. 600
  12. 2400
  13. 400
  14. 8100
  15. 1000
  16. 1200
  17. 2700
  18. 1600
  19. 6300
  20. 2700
  21. 1600
  22. 700
  23. 1300
  24. 2400
  25. 1800
  26. 3200
  27. 9000
  28. 1800
  29. 2800
  30. 900
  31. 1000
  32. 1500
  33. 900
  34. 2500
  35. 1300
  36. 900
  37. 600
  38. 8000
  39. 600
  40. 900

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