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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 382 · 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 87 × 66? (a) 630 (b) 63000 (c) 6300
  2. 2.Best estimate of 668 + 570? (a) 1500 (b) 1100 (c) 1300
  3. 3.Best estimate of 30 × 13? (a) 30 (b) 300 (c) 3000
  4. 4.Best estimate of 38 × 80? (a) 3200 (b) 32000 (c) 320
  5. 5.Best estimate of 13 × 19? (a) 200 (b) 2000 (c) 20
  6. 6.Best estimate of 41 × 18? (a) 800 (b) 8000 (c) 80
  7. 7.Best estimate of 81 × 38? (a) 3200 (b) 320 (c) 32000
  8. 8.Best estimate of 424 + 128? (a) 500 (b) 700 (c) 300
  9. 9.Best estimate of 590 + 646? (a) 1200 (b) 1000 (c) 1400
  10. 10.Best estimate of 31 × 27? (a) 9000 (b) 900 (c) 90
  11. 11.Best estimate of 301 + 153? (a) 700 (b) 500 (c) 300
  12. 12.Best estimate of 360 + 279? (a) 700 (b) 900 (c) 500
  13. 13.Best estimate of 182 + 508? (a) 500 (b) 900 (c) 700
  14. 14.Best estimate of 278 + 525? (a) 800 (b) 600 (c) 1000
  15. 15.Best estimate of 271 + 368? (a) 700 (b) 900 (c) 500
  16. 16.Best estimate of 79 × 74? (a) 5600 (b) 56000 (c) 560
  17. 17.Best estimate of 66 × 81? (a) 5600 (b) 56000 (c) 560
  18. 18.Best estimate of 375 + 586? (a) 1200 (b) 1000 (c) 800
  19. 19.Best estimate of 82 × 94? (a) 72000 (b) 7200 (c) 720
  20. 20.Best estimate of 473 + 587? (a) 1300 (b) 900 (c) 1100
  21. 21.Best estimate of 90 × 86? (a) 81000 (b) 8100 (c) 810
  22. 22.Best estimate of 541 + 238? (a) 900 (b) 700 (c) 500
  23. 23.Best estimate of 59 × 36? (a) 24000 (b) 2400 (c) 240
  24. 24.Best estimate of 376 + 196? (a) 600 (b) 800 (c) 400
  25. 25.Best estimate of 22 × 97? (a) 2000 (b) 20000 (c) 200
  26. 26.Best estimate of 392 + 184? (a) 400 (b) 600 (c) 800
  27. 27.Best estimate of 13 × 54? (a) 500 (b) 5000 (c) 50
  28. 28.Best estimate of 489 + 476? (a) 1200 (b) 1000 (c) 800
  29. 29.Best estimate of 364 + 228? (a) 600 (b) 400 (c) 800
  30. 30.Best estimate of 17 × 20? (a) 40 (b) 4000 (c) 400
  31. 31.Best estimate of 803 + 315? (a) 1300 (b) 1100 (c) 900
  32. 32.Best estimate of 91 × 32? (a) 270 (b) 2700 (c) 27000
  33. 33.Best estimate of 624 + 689? (a) 1100 (b) 1300 (c) 1500
  34. 34.Best estimate of 236 + 585? (a) 1000 (b) 600 (c) 800
  35. 35.Best estimate of 455 + 679? (a) 1400 (b) 1000 (c) 1200
  36. 36.Best estimate of 315 + 724? (a) 800 (b) 1200 (c) 1000
  37. 37.Best estimate of 66 × 37? (a) 2800 (b) 280 (c) 28000
  38. 38.Best estimate of 43 × 56? (a) 24000 (b) 2400 (c) 240
  39. 39.Best estimate of 400 + 659? (a) 1100 (b) 900 (c) 1300
  40. 40.Best estimate of 231 + 743? (a) 900 (b) 1100 (c) 700

Answer key

  1. 6300
  2. 1300
  3. 300
  4. 3200
  5. 200
  6. 800
  7. 3200
  8. 500
  9. 1200
  10. 900
  11. 500
  12. 700
  13. 700
  14. 800
  15. 700
  16. 5600
  17. 5600
  18. 1000
  19. 7200
  20. 1100
  21. 8100
  22. 700
  23. 2400
  24. 600
  25. 2000
  26. 600
  27. 500
  28. 1000
  29. 600
  30. 400
  31. 1100
  32. 2700
  33. 1300
  34. 800
  35. 1200
  36. 1000
  37. 2800
  38. 2400
  39. 1100
  40. 900

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