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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 184 · 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 56 × 48? (a) 3000 (b) 300 (c) 30000
  2. 2.Best estimate of 26 × 12? (a) 3000 (b) 300 (c) 30
  3. 3.Best estimate of 93 × 40? (a) 36000 (b) 3600 (c) 360
  4. 4.Best estimate of 58 × 33? (a) 1800 (b) 18000 (c) 180
  5. 5.Best estimate of 18 × 77? (a) 1600 (b) 160 (c) 16000
  6. 6.Best estimate of 43 × 26? (a) 120 (b) 12000 (c) 1200
  7. 7.Best estimate of 40 × 82? (a) 320 (b) 3200 (c) 32000
  8. 8.Best estimate of 83 × 26? (a) 24000 (b) 2400 (c) 240
  9. 9.Best estimate of 98 × 52? (a) 500 (b) 50000 (c) 5000
  10. 10.Best estimate of 692 + 386? (a) 1300 (b) 900 (c) 1100
  11. 11.Best estimate of 36 × 29? (a) 120 (b) 1200 (c) 12000
  12. 12.Best estimate of 19 × 87? (a) 18000 (b) 1800 (c) 180
  13. 13.Best estimate of 30 × 34? (a) 900 (b) 90 (c) 9000
  14. 14.Best estimate of 91 × 74? (a) 63000 (b) 630 (c) 6300
  15. 15.Best estimate of 381 + 614? (a) 1200 (b) 800 (c) 1000
  16. 16.Best estimate of 362 + 842? (a) 1200 (b) 1400 (c) 1000
  17. 17.Best estimate of 289 + 517? (a) 1000 (b) 600 (c) 800
  18. 18.Best estimate of 16 × 12? (a) 200 (b) 20 (c) 2000
  19. 19.Best estimate of 760 + 623? (a) 1200 (b) 1600 (c) 1400
  20. 20.Best estimate of 368 + 860? (a) 1500 (b) 1100 (c) 1300
  21. 21.Best estimate of 70 × 46? (a) 35000 (b) 3500 (c) 350
  22. 22.Best estimate of 393 + 277? (a) 900 (b) 700 (c) 500
  23. 23.Best estimate of 344 + 480? (a) 1000 (b) 800 (c) 600
  24. 24.Best estimate of 561 + 751? (a) 1600 (b) 1200 (c) 1400
  25. 25.Best estimate of 16 × 42? (a) 800 (b) 80 (c) 8000
  26. 26.Best estimate of 83 × 27? (a) 24000 (b) 240 (c) 2400
  27. 27.Best estimate of 740 + 128? (a) 1000 (b) 600 (c) 800
  28. 28.Best estimate of 606 + 420? (a) 800 (b) 1200 (c) 1000
  29. 29.Best estimate of 176 + 442? (a) 800 (b) 600 (c) 400
  30. 30.Best estimate of 81 × 69? (a) 560 (b) 56000 (c) 5600
  31. 31.Best estimate of 838 + 692? (a) 1700 (b) 1300 (c) 1500
  32. 32.Best estimate of 34 × 23? (a) 600 (b) 6000 (c) 60
  33. 33.Best estimate of 582 + 456? (a) 1300 (b) 1100 (c) 900
  34. 34.Best estimate of 93 × 58? (a) 540 (b) 5400 (c) 54000
  35. 35.Best estimate of 702 + 760? (a) 1300 (b) 1700 (c) 1500
  36. 36.Best estimate of 316 + 323? (a) 800 (b) 400 (c) 600
  37. 37.Best estimate of 336 + 646? (a) 700 (b) 1100 (c) 900
  38. 38.Best estimate of 332 + 596? (a) 900 (b) 1100 (c) 700
  39. 39.Best estimate of 86 × 14? (a) 90 (b) 900 (c) 9000
  40. 40.Best estimate of 57 × 87? (a) 54000 (b) 540 (c) 5400

Answer key

  1. 3000
  2. 300
  3. 3600
  4. 1800
  5. 1600
  6. 1200
  7. 3200
  8. 2400
  9. 5000
  10. 1100
  11. 1200
  12. 1800
  13. 900
  14. 6300
  15. 1000
  16. 1200
  17. 800
  18. 200
  19. 1400
  20. 1300
  21. 3500
  22. 700
  23. 800
  24. 1400
  25. 800
  26. 2400
  27. 800
  28. 1000
  29. 600
  30. 5600
  31. 1500
  32. 600
  33. 1100
  34. 5400
  35. 1500
  36. 600
  37. 900
  38. 900
  39. 900
  40. 5400

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