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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 605 · 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 23 × 84? (a) 1600 (b) 16000 (c) 160
  2. 2.Best estimate of 720 + 309? (a) 1200 (b) 800 (c) 1000
  3. 3.Best estimate of 13 × 29? (a) 3000 (b) 300 (c) 30
  4. 4.Best estimate of 582 + 817? (a) 1400 (b) 1200 (c) 1600
  5. 5.Best estimate of 218 + 634? (a) 800 (b) 1000 (c) 600
  6. 6.Best estimate of 608 + 346? (a) 1100 (b) 900 (c) 700
  7. 7.Best estimate of 521 + 567? (a) 1300 (b) 900 (c) 1100
  8. 8.Best estimate of 655 + 714? (a) 1400 (b) 1600 (c) 1200
  9. 9.Best estimate of 57 × 14? (a) 6000 (b) 60 (c) 600
  10. 10.Best estimate of 89 × 43? (a) 3600 (b) 36000 (c) 360
  11. 11.Best estimate of 89 × 71? (a) 630 (b) 6300 (c) 63000
  12. 12.Best estimate of 17 × 43? (a) 80 (b) 800 (c) 8000
  13. 13.Best estimate of 56 × 76? (a) 480 (b) 48000 (c) 4800
  14. 14.Best estimate of 33 × 34? (a) 900 (b) 9000 (c) 90
  15. 15.Best estimate of 20 × 56? (a) 1200 (b) 12000 (c) 120
  16. 16.Best estimate of 52 × 23? (a) 1000 (b) 10000 (c) 100
  17. 17.Best estimate of 745 + 274? (a) 1000 (b) 1200 (c) 800
  18. 18.Best estimate of 16 × 71? (a) 140 (b) 1400 (c) 14000
  19. 19.Best estimate of 69 × 54? (a) 35000 (b) 3500 (c) 350
  20. 20.Best estimate of 161 + 586? (a) 1000 (b) 600 (c) 800
  21. 21.Best estimate of 638 + 497? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 13 × 69? (a) 70 (b) 7000 (c) 700
  23. 23.Best estimate of 18 × 63? (a) 120 (b) 12000 (c) 1200
  24. 24.Best estimate of 135 + 234? (a) 300 (b) 500 (c) 100
  25. 25.Best estimate of 89 × 64? (a) 54000 (b) 5400 (c) 540
  26. 26.Best estimate of 672 + 146? (a) 1000 (b) 800 (c) 600
  27. 27.Best estimate of 370 + 352? (a) 1000 (b) 600 (c) 800
  28. 28.Best estimate of 38 × 77? (a) 320 (b) 3200 (c) 32000
  29. 29.Best estimate of 53 × 97? (a) 500 (b) 50000 (c) 5000
  30. 30.Best estimate of 89 × 23? (a) 1800 (b) 180 (c) 18000
  31. 31.Best estimate of 592 + 790? (a) 1600 (b) 1200 (c) 1400
  32. 32.Best estimate of 736 + 618? (a) 1300 (b) 1100 (c) 1500
  33. 33.Best estimate of 20 × 18? (a) 40 (b) 400 (c) 4000
  34. 34.Best estimate of 413 + 225? (a) 400 (b) 600 (c) 800
  35. 35.Best estimate of 13 × 92? (a) 900 (b) 90 (c) 9000
  36. 36.Best estimate of 84 × 66? (a) 5600 (b) 56000 (c) 560
  37. 37.Best estimate of 263 + 503? (a) 1000 (b) 800 (c) 600
  38. 38.Best estimate of 90 × 72? (a) 630 (b) 63000 (c) 6300
  39. 39.Best estimate of 197 + 229? (a) 600 (b) 200 (c) 400
  40. 40.Best estimate of 681 + 508? (a) 1200 (b) 1400 (c) 1000

Answer key

  1. 1600
  2. 1000
  3. 300
  4. 1400
  5. 800
  6. 900
  7. 1100
  8. 1400
  9. 600
  10. 3600
  11. 6300
  12. 800
  13. 4800
  14. 900
  15. 1200
  16. 1000
  17. 1000
  18. 1400
  19. 3500
  20. 800
  21. 1100
  22. 700
  23. 1200
  24. 300
  25. 5400
  26. 800
  27. 800
  28. 3200
  29. 5000
  30. 1800
  31. 1400
  32. 1300
  33. 400
  34. 600
  35. 900
  36. 5600
  37. 800
  38. 6300
  39. 400
  40. 1200

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