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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 212 · 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 84 × 26? (a) 240 (b) 24000 (c) 2400
  2. 2.Best estimate of 54 × 81? (a) 40000 (b) 400 (c) 4000
  3. 3.Best estimate of 41 × 76? (a) 3200 (b) 320 (c) 32000
  4. 4.Best estimate of 588 + 165? (a) 600 (b) 800 (c) 1000
  5. 5.Best estimate of 477 + 179? (a) 700 (b) 900 (c) 500
  6. 6.Best estimate of 74 × 22? (a) 14000 (b) 140 (c) 1400
  7. 7.Best estimate of 378 + 507? (a) 1100 (b) 900 (c) 700
  8. 8.Best estimate of 27 × 69? (a) 2100 (b) 21000 (c) 210
  9. 9.Best estimate of 387 + 863? (a) 1500 (b) 1100 (c) 1300
  10. 10.Best estimate of 46 × 84? (a) 4000 (b) 40000 (c) 400
  11. 11.Best estimate of 496 + 474? (a) 1200 (b) 800 (c) 1000
  12. 12.Best estimate of 26 × 36? (a) 120 (b) 12000 (c) 1200
  13. 13.Best estimate of 596 + 162? (a) 1000 (b) 600 (c) 800
  14. 14.Best estimate of 388 + 788? (a) 1200 (b) 1400 (c) 1000
  15. 15.Best estimate of 42 × 26? (a) 120 (b) 1200 (c) 12000
  16. 16.Best estimate of 51 × 72? (a) 35000 (b) 3500 (c) 350
  17. 17.Best estimate of 79 × 56? (a) 480 (b) 48000 (c) 4800
  18. 18.Best estimate of 96 × 70? (a) 700 (b) 7000 (c) 70000
  19. 19.Best estimate of 37 × 94? (a) 360 (b) 36000 (c) 3600
  20. 20.Best estimate of 74 × 20? (a) 140 (b) 14000 (c) 1400
  21. 21.Best estimate of 553 + 278? (a) 700 (b) 1100 (c) 900
  22. 22.Best estimate of 26 × 73? (a) 210 (b) 2100 (c) 21000
  23. 23.Best estimate of 24 × 87? (a) 1800 (b) 180 (c) 18000
  24. 24.Best estimate of 673 + 815? (a) 1500 (b) 1700 (c) 1300
  25. 25.Best estimate of 127 + 220? (a) 300 (b) 100 (c) 500
  26. 26.Best estimate of 84 × 22? (a) 16000 (b) 160 (c) 1600
  27. 27.Best estimate of 168 + 864? (a) 1300 (b) 1100 (c) 900
  28. 28.Best estimate of 19 × 83? (a) 160 (b) 1600 (c) 16000
  29. 29.Best estimate of 337 + 208? (a) 700 (b) 500 (c) 300
  30. 30.Best estimate of 579 + 821? (a) 1600 (b) 1200 (c) 1400
  31. 31.Best estimate of 36 × 34? (a) 1200 (b) 120 (c) 12000
  32. 32.Best estimate of 446 + 703? (a) 900 (b) 1300 (c) 1100
  33. 33.Best estimate of 869 + 132? (a) 800 (b) 1000 (c) 1200
  34. 34.Best estimate of 546 + 383? (a) 700 (b) 1100 (c) 900
  35. 35.Best estimate of 707 + 141? (a) 600 (b) 800 (c) 1000
  36. 36.Best estimate of 797 + 544? (a) 1500 (b) 1100 (c) 1300
  37. 37.Best estimate of 73 × 58? (a) 42000 (b) 4200 (c) 420
  38. 38.Best estimate of 685 + 776? (a) 1500 (b) 1700 (c) 1300
  39. 39.Best estimate of 472 + 399? (a) 1100 (b) 700 (c) 900
  40. 40.Best estimate of 34 × 91? (a) 2700 (b) 270 (c) 27000

Answer key

  1. 2400
  2. 4000
  3. 3200
  4. 800
  5. 700
  6. 1400
  7. 900
  8. 2100
  9. 1300
  10. 4000
  11. 1000
  12. 1200
  13. 800
  14. 1200
  15. 1200
  16. 3500
  17. 4800
  18. 7000
  19. 3600
  20. 1400
  21. 900
  22. 2100
  23. 1800
  24. 1500
  25. 300
  26. 1600
  27. 1100
  28. 1600
  29. 500
  30. 1400
  31. 1200
  32. 1100
  33. 1000
  34. 900
  35. 800
  36. 1300
  37. 4200
  38. 1500
  39. 900
  40. 2700

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