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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 809 · 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 12 × 66? (a) 7000 (b) 70 (c) 700
  2. 2.Best estimate of 87 × 37? (a) 36000 (b) 3600 (c) 360
  3. 3.Best estimate of 133 + 427? (a) 700 (b) 500 (c) 300
  4. 4.Best estimate of 136 + 248? (a) 100 (b) 300 (c) 500
  5. 5.Best estimate of 88 × 60? (a) 540 (b) 54000 (c) 5400
  6. 6.Best estimate of 71 × 27? (a) 210 (b) 2100 (c) 21000
  7. 7.Best estimate of 23 × 41? (a) 80 (b) 8000 (c) 800
  8. 8.Best estimate of 671 + 153? (a) 700 (b) 1100 (c) 900
  9. 9.Best estimate of 48 × 38? (a) 20000 (b) 200 (c) 2000
  10. 10.Best estimate of 868 + 357? (a) 1300 (b) 1100 (c) 1500
  11. 11.Best estimate of 47 × 56? (a) 300 (b) 30000 (c) 3000
  12. 12.Best estimate of 98 × 88? (a) 9000 (b) 90000 (c) 900
  13. 13.Best estimate of 61 × 76? (a) 48000 (b) 480 (c) 4800
  14. 14.Best estimate of 376 + 545? (a) 1100 (b) 900 (c) 700
  15. 15.Best estimate of 736 + 729? (a) 1400 (b) 1600 (c) 1200
  16. 16.Best estimate of 679 + 322? (a) 1000 (b) 800 (c) 1200
  17. 17.Best estimate of 498 + 273? (a) 600 (b) 800 (c) 1000
  18. 18.Best estimate of 672 + 858? (a) 1400 (b) 1600 (c) 1800
  19. 19.Best estimate of 686 + 802? (a) 1700 (b) 1500 (c) 1300
  20. 20.Best estimate of 26 × 97? (a) 3000 (b) 30000 (c) 300
  21. 21.Best estimate of 60 × 89? (a) 54000 (b) 5400 (c) 540
  22. 22.Best estimate of 773 + 851? (a) 1900 (b) 1500 (c) 1700
  23. 23.Best estimate of 72 × 20? (a) 140 (b) 14000 (c) 1400
  24. 24.Best estimate of 397 + 587? (a) 1000 (b) 1200 (c) 800
  25. 25.Best estimate of 366 + 267? (a) 500 (b) 900 (c) 700
  26. 26.Best estimate of 877 + 819? (a) 1500 (b) 1700 (c) 1900
  27. 27.Best estimate of 69 × 16? (a) 1400 (b) 14000 (c) 140
  28. 28.Best estimate of 18 × 61? (a) 1200 (b) 12000 (c) 120
  29. 29.Best estimate of 546 + 515? (a) 800 (b) 1200 (c) 1000
  30. 30.Best estimate of 66 × 57? (a) 420 (b) 4200 (c) 42000
  31. 31.Best estimate of 231 + 275? (a) 700 (b) 300 (c) 500
  32. 32.Best estimate of 62 × 82? (a) 4800 (b) 48000 (c) 480
  33. 33.Best estimate of 545 + 747? (a) 1000 (b) 1200 (c) 1400
  34. 34.Best estimate of 543 + 443? (a) 700 (b) 1100 (c) 900
  35. 35.Best estimate of 18 × 49? (a) 10000 (b) 1000 (c) 100
  36. 36.Best estimate of 381 + 245? (a) 600 (b) 800 (c) 400
  37. 37.Best estimate of 468 + 420? (a) 900 (b) 700 (c) 1100
  38. 38.Best estimate of 64 × 56? (a) 36000 (b) 360 (c) 3600
  39. 39.Best estimate of 26 × 89? (a) 2700 (b) 270 (c) 27000
  40. 40.Best estimate of 360 + 122? (a) 500 (b) 300 (c) 700

Answer key

  1. 700
  2. 3600
  3. 500
  4. 300
  5. 5400
  6. 2100
  7. 800
  8. 900
  9. 2000
  10. 1300
  11. 3000
  12. 9000
  13. 4800
  14. 900
  15. 1400
  16. 1000
  17. 800
  18. 1600
  19. 1500
  20. 3000
  21. 5400
  22. 1700
  23. 1400
  24. 1000
  25. 700
  26. 1700
  27. 1400
  28. 1200
  29. 1000
  30. 4200
  31. 500
  32. 4800
  33. 1200
  34. 900
  35. 1000
  36. 600
  37. 900
  38. 3600
  39. 2700
  40. 500

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