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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 324 · 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 59 × 28? (a) 180 (b) 18000 (c) 1800
  2. 2.Best estimate of 61 × 92? (a) 540 (b) 5400 (c) 54000
  3. 3.Best estimate of 70 × 33? (a) 21000 (b) 210 (c) 2100
  4. 4.Best estimate of 47 × 37? (a) 200 (b) 2000 (c) 20000
  5. 5.Best estimate of 96 × 52? (a) 500 (b) 5000 (c) 50000
  6. 6.Best estimate of 875 + 412? (a) 1300 (b) 1100 (c) 1500
  7. 7.Best estimate of 37 × 16? (a) 8000 (b) 80 (c) 800
  8. 8.Best estimate of 66 × 88? (a) 63000 (b) 6300 (c) 630
  9. 9.Best estimate of 555 + 316? (a) 700 (b) 1100 (c) 900
  10. 10.Best estimate of 355 + 500? (a) 700 (b) 900 (c) 1100
  11. 11.Best estimate of 744 + 660? (a) 1200 (b) 1600 (c) 1400
  12. 12.Best estimate of 421 + 859? (a) 1500 (b) 1300 (c) 1100
  13. 13.Best estimate of 333 + 517? (a) 1000 (b) 600 (c) 800
  14. 14.Best estimate of 46 × 61? (a) 3000 (b) 300 (c) 30000
  15. 15.Best estimate of 71 × 56? (a) 42000 (b) 420 (c) 4200
  16. 16.Best estimate of 17 × 42? (a) 8000 (b) 800 (c) 80
  17. 17.Best estimate of 501 + 733? (a) 1200 (b) 1000 (c) 1400
  18. 18.Best estimate of 207 + 342? (a) 300 (b) 700 (c) 500
  19. 19.Best estimate of 86 × 94? (a) 810 (b) 8100 (c) 81000
  20. 20.Best estimate of 81 × 60? (a) 4800 (b) 480 (c) 48000
  21. 21.Best estimate of 179 + 264? (a) 300 (b) 700 (c) 500
  22. 22.Best estimate of 38 × 97? (a) 40000 (b) 400 (c) 4000
  23. 23.Best estimate of 90 × 91? (a) 8100 (b) 810 (c) 81000
  24. 24.Best estimate of 57 × 36? (a) 240 (b) 24000 (c) 2400
  25. 25.Best estimate of 485 + 654? (a) 1400 (b) 1000 (c) 1200
  26. 26.Best estimate of 305 + 565? (a) 1100 (b) 900 (c) 700
  27. 27.Best estimate of 47 × 53? (a) 25000 (b) 2500 (c) 250
  28. 28.Best estimate of 47 × 12? (a) 500 (b) 50 (c) 5000
  29. 29.Best estimate of 74 × 13? (a) 7000 (b) 70 (c) 700
  30. 30.Best estimate of 324 + 542? (a) 800 (b) 600 (c) 1000
  31. 31.Best estimate of 154 + 499? (a) 900 (b) 700 (c) 500
  32. 32.Best estimate of 61 × 84? (a) 48000 (b) 4800 (c) 480
  33. 33.Best estimate of 396 + 162? (a) 800 (b) 400 (c) 600
  34. 34.Best estimate of 753 + 785? (a) 1800 (b) 1600 (c) 1400
  35. 35.Best estimate of 543 + 309? (a) 1000 (b) 800 (c) 600
  36. 36.Best estimate of 34 × 39? (a) 12000 (b) 1200 (c) 120
  37. 37.Best estimate of 312 + 483? (a) 600 (b) 1000 (c) 800
  38. 38.Best estimate of 56 × 42? (a) 24000 (b) 2400 (c) 240
  39. 39.Best estimate of 431 + 762? (a) 1000 (b) 1200 (c) 1400
  40. 40.Best estimate of 446 + 290? (a) 700 (b) 500 (c) 900

Answer key

  1. 1800
  2. 5400
  3. 2100
  4. 2000
  5. 5000
  6. 1300
  7. 800
  8. 6300
  9. 900
  10. 900
  11. 1400
  12. 1300
  13. 800
  14. 3000
  15. 4200
  16. 800
  17. 1200
  18. 500
  19. 8100
  20. 4800
  21. 500
  22. 4000
  23. 8100
  24. 2400
  25. 1200
  26. 900
  27. 2500
  28. 500
  29. 700
  30. 800
  31. 700
  32. 4800
  33. 600
  34. 1600
  35. 800
  36. 1200
  37. 800
  38. 2400
  39. 1200
  40. 700

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