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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 432 · 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 210 + 200? (a) 600 (b) 200 (c) 400
  2. 2.Best estimate of 729 + 267? (a) 1000 (b) 800 (c) 1200
  3. 3.Best estimate of 61 × 93? (a) 54000 (b) 5400 (c) 540
  4. 4.Best estimate of 23 × 69? (a) 14000 (b) 140 (c) 1400
  5. 5.Best estimate of 803 + 240? (a) 1000 (b) 1200 (c) 800
  6. 6.Best estimate of 488 + 810? (a) 1300 (b) 1500 (c) 1100
  7. 7.Best estimate of 21 × 79? (a) 160 (b) 1600 (c) 16000
  8. 8.Best estimate of 37 × 76? (a) 320 (b) 3200 (c) 32000
  9. 9.Best estimate of 506 + 134? (a) 400 (b) 600 (c) 800
  10. 10.Best estimate of 442 + 831? (a) 1400 (b) 1000 (c) 1200
  11. 11.Best estimate of 47 × 82? (a) 4000 (b) 40000 (c) 400
  12. 12.Best estimate of 306 + 708? (a) 1200 (b) 1000 (c) 800
  13. 13.Best estimate of 280 + 309? (a) 600 (b) 400 (c) 800
  14. 14.Best estimate of 125 + 412? (a) 700 (b) 300 (c) 500
  15. 15.Best estimate of 67 × 78? (a) 56000 (b) 560 (c) 5600
  16. 16.Best estimate of 456 + 628? (a) 1100 (b) 900 (c) 1300
  17. 17.Best estimate of 202 + 792? (a) 1200 (b) 800 (c) 1000
  18. 18.Best estimate of 97 × 30? (a) 300 (b) 30000 (c) 3000
  19. 19.Best estimate of 73 × 67? (a) 4900 (b) 490 (c) 49000
  20. 20.Best estimate of 40 × 90? (a) 36000 (b) 360 (c) 3600
  21. 21.Best estimate of 20 × 27? (a) 600 (b) 60 (c) 6000
  22. 22.Best estimate of 86 × 18? (a) 1800 (b) 18000 (c) 180
  23. 23.Best estimate of 420 + 762? (a) 1000 (b) 1200 (c) 1400
  24. 24.Best estimate of 463 + 179? (a) 900 (b) 700 (c) 500
  25. 25.Best estimate of 524 + 279? (a) 800 (b) 1000 (c) 600
  26. 26.Best estimate of 337 + 214? (a) 500 (b) 700 (c) 300
  27. 27.Best estimate of 23 × 23? (a) 40 (b) 4000 (c) 400
  28. 28.Best estimate of 29 × 24? (a) 60 (b) 6000 (c) 600
  29. 29.Best estimate of 454 + 312? (a) 600 (b) 800 (c) 1000
  30. 30.Best estimate of 779 + 383? (a) 1200 (b) 1400 (c) 1000
  31. 31.Best estimate of 41 × 26? (a) 1200 (b) 120 (c) 12000
  32. 32.Best estimate of 26 × 41? (a) 12000 (b) 1200 (c) 120
  33. 33.Best estimate of 453 + 303? (a) 800 (b) 600 (c) 1000
  34. 34.Best estimate of 308 + 684? (a) 1000 (b) 800 (c) 1200
  35. 35.Best estimate of 567 + 326? (a) 900 (b) 1100 (c) 700
  36. 36.Best estimate of 72 × 47? (a) 3500 (b) 35000 (c) 350
  37. 37.Best estimate of 18 × 93? (a) 1800 (b) 18000 (c) 180
  38. 38.Best estimate of 270 + 832? (a) 1100 (b) 900 (c) 1300
  39. 39.Best estimate of 376 + 204? (a) 600 (b) 400 (c) 800
  40. 40.Best estimate of 36 × 81? (a) 320 (b) 32000 (c) 3200

Answer key

  1. 400
  2. 1000
  3. 5400
  4. 1400
  5. 1000
  6. 1300
  7. 1600
  8. 3200
  9. 600
  10. 1200
  11. 4000
  12. 1000
  13. 600
  14. 500
  15. 5600
  16. 1100
  17. 1000
  18. 3000
  19. 4900
  20. 3600
  21. 600
  22. 1800
  23. 1200
  24. 700
  25. 800
  26. 500
  27. 400
  28. 600
  29. 800
  30. 1200
  31. 1200
  32. 1200
  33. 800
  34. 1000
  35. 900
  36. 3500
  37. 1800
  38. 1100
  39. 600
  40. 3200

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