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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 590 · 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 325 + 299? (a) 600 (b) 800 (c) 400
  2. 2.Best estimate of 64 × 86? (a) 5400 (b) 54000 (c) 540
  3. 3.Best estimate of 678 + 758? (a) 1500 (b) 1300 (c) 1700
  4. 4.Best estimate of 29 × 68? (a) 2100 (b) 210 (c) 21000
  5. 5.Best estimate of 69 × 60? (a) 4200 (b) 42000 (c) 420
  6. 6.Best estimate of 876 + 131? (a) 800 (b) 1200 (c) 1000
  7. 7.Best estimate of 668 + 424? (a) 900 (b) 1100 (c) 1300
  8. 8.Best estimate of 208 + 796? (a) 1200 (b) 1000 (c) 800
  9. 9.Best estimate of 314 + 291? (a) 400 (b) 600 (c) 800
  10. 10.Best estimate of 21 × 66? (a) 14000 (b) 140 (c) 1400
  11. 11.Best estimate of 387 + 231? (a) 600 (b) 800 (c) 400
  12. 12.Best estimate of 205 + 490? (a) 700 (b) 500 (c) 900
  13. 13.Best estimate of 90 × 12? (a) 9000 (b) 900 (c) 90
  14. 14.Best estimate of 273 + 459? (a) 600 (b) 1000 (c) 800
  15. 15.Best estimate of 22 × 56? (a) 1200 (b) 120 (c) 12000
  16. 16.Best estimate of 13 × 39? (a) 4000 (b) 40 (c) 400
  17. 17.Best estimate of 67 × 56? (a) 420 (b) 42000 (c) 4200
  18. 18.Best estimate of 751 + 504? (a) 1300 (b) 1100 (c) 1500
  19. 19.Best estimate of 29 × 56? (a) 180 (b) 18000 (c) 1800
  20. 20.Best estimate of 830 + 357? (a) 1000 (b) 1200 (c) 1400
  21. 21.Best estimate of 502 + 192? (a) 500 (b) 900 (c) 700
  22. 22.Best estimate of 96 × 26? (a) 3000 (b) 30000 (c) 300
  23. 23.Best estimate of 538 + 287? (a) 800 (b) 1000 (c) 600
  24. 24.Best estimate of 857 + 749? (a) 1800 (b) 1400 (c) 1600
  25. 25.Best estimate of 441 + 757? (a) 1400 (b) 1200 (c) 1000
  26. 26.Best estimate of 226 + 392? (a) 400 (b) 600 (c) 800
  27. 27.Best estimate of 23 × 18? (a) 40 (b) 4000 (c) 400
  28. 28.Best estimate of 70 × 26? (a) 210 (b) 21000 (c) 2100
  29. 29.Best estimate of 592 + 362? (a) 1000 (b) 1200 (c) 800
  30. 30.Best estimate of 473 + 495? (a) 1200 (b) 1000 (c) 800
  31. 31.Best estimate of 49 × 73? (a) 350 (b) 35000 (c) 3500
  32. 32.Best estimate of 30 × 92? (a) 27000 (b) 2700 (c) 270
  33. 33.Best estimate of 74 × 31? (a) 21000 (b) 210 (c) 2100
  34. 34.Best estimate of 279 + 808? (a) 1100 (b) 900 (c) 1300
  35. 35.Best estimate of 661 + 494? (a) 1200 (b) 1000 (c) 1400
  36. 36.Best estimate of 28 × 34? (a) 9000 (b) 900 (c) 90
  37. 37.Best estimate of 52 × 16? (a) 1000 (b) 10000 (c) 100
  38. 38.Best estimate of 98 × 66? (a) 70000 (b) 7000 (c) 700
  39. 39.Best estimate of 328 + 833? (a) 1300 (b) 900 (c) 1100
  40. 40.Best estimate of 74 × 86? (a) 630 (b) 6300 (c) 63000

Answer key

  1. 600
  2. 5400
  3. 1500
  4. 2100
  5. 4200
  6. 1000
  7. 1100
  8. 1000
  9. 600
  10. 1400
  11. 600
  12. 700
  13. 900
  14. 800
  15. 1200
  16. 400
  17. 4200
  18. 1300
  19. 1800
  20. 1200
  21. 700
  22. 3000
  23. 800
  24. 1600
  25. 1200
  26. 600
  27. 400
  28. 2100
  29. 1000
  30. 1000
  31. 3500
  32. 2700
  33. 2100
  34. 1100
  35. 1200
  36. 900
  37. 1000
  38. 7000
  39. 1100
  40. 6300

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