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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 416 · 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 137 + 273? (a) 400 (b) 200 (c) 600
  2. 2.Best estimate of 140 + 424? (a) 500 (b) 700 (c) 300
  3. 3.Best estimate of 307 + 530? (a) 1000 (b) 800 (c) 600
  4. 4.Best estimate of 90 × 20? (a) 1800 (b) 18000 (c) 180
  5. 5.Best estimate of 93 × 36? (a) 3600 (b) 36000 (c) 360
  6. 6.Best estimate of 22 × 12? (a) 200 (b) 2000 (c) 20
  7. 7.Best estimate of 507 + 557? (a) 1100 (b) 1300 (c) 900
  8. 8.Best estimate of 40 × 69? (a) 2800 (b) 280 (c) 28000
  9. 9.Best estimate of 93 × 92? (a) 8100 (b) 81000 (c) 810
  10. 10.Best estimate of 54 × 67? (a) 35000 (b) 3500 (c) 350
  11. 11.Best estimate of 636 + 764? (a) 1600 (b) 1200 (c) 1400
  12. 12.Best estimate of 69 × 89? (a) 630 (b) 63000 (c) 6300
  13. 13.Best estimate of 86 × 56? (a) 540 (b) 54000 (c) 5400
  14. 14.Best estimate of 62 × 64? (a) 3600 (b) 360 (c) 36000
  15. 15.Best estimate of 682 + 287? (a) 1000 (b) 1200 (c) 800
  16. 16.Best estimate of 19 × 74? (a) 14000 (b) 1400 (c) 140
  17. 17.Best estimate of 194 + 234? (a) 400 (b) 200 (c) 600
  18. 18.Best estimate of 49 × 47? (a) 2500 (b) 250 (c) 25000
  19. 19.Best estimate of 690 + 612? (a) 1500 (b) 1100 (c) 1300
  20. 20.Best estimate of 36 × 76? (a) 32000 (b) 320 (c) 3200
  21. 21.Best estimate of 51 × 40? (a) 20000 (b) 2000 (c) 200
  22. 22.Best estimate of 81 × 56? (a) 48000 (b) 4800 (c) 480
  23. 23.Best estimate of 44 × 63? (a) 2400 (b) 24000 (c) 240
  24. 24.Best estimate of 531 + 497? (a) 1200 (b) 1000 (c) 800
  25. 25.Best estimate of 358 + 727? (a) 1300 (b) 900 (c) 1100
  26. 26.Best estimate of 26 × 84? (a) 24000 (b) 2400 (c) 240
  27. 27.Best estimate of 295 + 451? (a) 1000 (b) 800 (c) 600
  28. 28.Best estimate of 608 + 761? (a) 1400 (b) 1600 (c) 1200
  29. 29.Best estimate of 419 + 838? (a) 1000 (b) 1400 (c) 1200
  30. 30.Best estimate of 391 + 568? (a) 1200 (b) 800 (c) 1000
  31. 31.Best estimate of 174 + 406? (a) 600 (b) 800 (c) 400
  32. 32.Best estimate of 775 + 797? (a) 1800 (b) 1400 (c) 1600
  33. 33.Best estimate of 576 + 769? (a) 1200 (b) 1600 (c) 1400
  34. 34.Best estimate of 80 × 78? (a) 6400 (b) 64000 (c) 640
  35. 35.Best estimate of 12 × 89? (a) 900 (b) 9000 (c) 90
  36. 36.Best estimate of 98 × 43? (a) 40000 (b) 4000 (c) 400
  37. 37.Best estimate of 464 + 670? (a) 1000 (b) 1200 (c) 1400
  38. 38.Best estimate of 24 × 56? (a) 120 (b) 12000 (c) 1200
  39. 39.Best estimate of 69 × 71? (a) 4900 (b) 49000 (c) 490
  40. 40.Best estimate of 327 + 540? (a) 800 (b) 600 (c) 1000

Answer key

  1. 400
  2. 500
  3. 800
  4. 1800
  5. 3600
  6. 200
  7. 1100
  8. 2800
  9. 8100
  10. 3500
  11. 1400
  12. 6300
  13. 5400
  14. 3600
  15. 1000
  16. 1400
  17. 400
  18. 2500
  19. 1300
  20. 3200
  21. 2000
  22. 4800
  23. 2400
  24. 1000
  25. 1100
  26. 2400
  27. 800
  28. 1400
  29. 1200
  30. 1000
  31. 600
  32. 1600
  33. 1400
  34. 6400
  35. 900
  36. 4000
  37. 1200
  38. 1200
  39. 4900
  40. 800

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