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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 491 · 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 86 × 86? (a) 8100 (b) 810 (c) 81000
  2. 2.Best estimate of 287 + 454? (a) 1000 (b) 600 (c) 800
  3. 3.Best estimate of 814 + 547? (a) 1300 (b) 1100 (c) 1500
  4. 4.Best estimate of 421 + 189? (a) 800 (b) 400 (c) 600
  5. 5.Best estimate of 96 × 37? (a) 4000 (b) 40000 (c) 400
  6. 6.Best estimate of 320 + 216? (a) 500 (b) 300 (c) 700
  7. 7.Best estimate of 13 × 80? (a) 80 (b) 800 (c) 8000
  8. 8.Best estimate of 483 + 490? (a) 1200 (b) 800 (c) 1000
  9. 9.Best estimate of 613 + 680? (a) 1500 (b) 1100 (c) 1300
  10. 10.Best estimate of 69 × 26? (a) 2100 (b) 210 (c) 21000
  11. 11.Best estimate of 30 × 24? (a) 60 (b) 6000 (c) 600
  12. 12.Best estimate of 141 + 126? (a) 200 (b) 400 (c) 0
  13. 13.Best estimate of 688 + 286? (a) 1200 (b) 800 (c) 1000
  14. 14.Best estimate of 304 + 366? (a) 500 (b) 700 (c) 900
  15. 15.Best estimate of 84 × 23? (a) 160 (b) 1600 (c) 16000
  16. 16.Best estimate of 72 × 82? (a) 560 (b) 56000 (c) 5600
  17. 17.Best estimate of 181 + 278? (a) 700 (b) 300 (c) 500
  18. 18.Best estimate of 61 × 61? (a) 360 (b) 36000 (c) 3600
  19. 19.Best estimate of 759 + 748? (a) 1300 (b) 1500 (c) 1700
  20. 20.Best estimate of 22 × 47? (a) 1000 (b) 100 (c) 10000
  21. 21.Best estimate of 80 × 82? (a) 6400 (b) 640 (c) 64000
  22. 22.Best estimate of 42 × 67? (a) 280 (b) 2800 (c) 28000
  23. 23.Best estimate of 442 + 841? (a) 1400 (b) 1000 (c) 1200
  24. 24.Best estimate of 93 × 18? (a) 180 (b) 1800 (c) 18000
  25. 25.Best estimate of 76 × 84? (a) 6400 (b) 64000 (c) 640
  26. 26.Best estimate of 185 + 390? (a) 600 (b) 400 (c) 800
  27. 27.Best estimate of 728 + 855? (a) 1400 (b) 1800 (c) 1600
  28. 28.Best estimate of 49 × 71? (a) 350 (b) 35000 (c) 3500
  29. 29.Best estimate of 18 × 60? (a) 1200 (b) 120 (c) 12000
  30. 30.Best estimate of 33 × 77? (a) 240 (b) 2400 (c) 24000
  31. 31.Best estimate of 69 × 98? (a) 70000 (b) 700 (c) 7000
  32. 32.Best estimate of 804 + 424? (a) 1000 (b) 1400 (c) 1200
  33. 33.Best estimate of 47 × 32? (a) 1500 (b) 15000 (c) 150
  34. 34.Best estimate of 518 + 455? (a) 1000 (b) 1200 (c) 800
  35. 35.Best estimate of 293 + 446? (a) 700 (b) 900 (c) 500
  36. 36.Best estimate of 200 + 488? (a) 700 (b) 500 (c) 900
  37. 37.Best estimate of 14 × 28? (a) 3000 (b) 300 (c) 30
  38. 38.Best estimate of 21 × 41? (a) 800 (b) 8000 (c) 80
  39. 39.Best estimate of 748 + 203? (a) 700 (b) 900 (c) 1100
  40. 40.Best estimate of 415 + 427? (a) 1000 (b) 800 (c) 600

Answer key

  1. 8100
  2. 800
  3. 1300
  4. 600
  5. 4000
  6. 500
  7. 800
  8. 1000
  9. 1300
  10. 2100
  11. 600
  12. 200
  13. 1000
  14. 700
  15. 1600
  16. 5600
  17. 500
  18. 3600
  19. 1500
  20. 1000
  21. 6400
  22. 2800
  23. 1200
  24. 1800
  25. 6400
  26. 600
  27. 1600
  28. 3500
  29. 1200
  30. 2400
  31. 7000
  32. 1200
  33. 1500
  34. 1000
  35. 700
  36. 700
  37. 300
  38. 800
  39. 900
  40. 800

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