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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 594 · 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 329 + 501? (a) 600 (b) 1000 (c) 800
  2. 2.Best estimate of 23 × 48? (a) 100 (b) 10000 (c) 1000
  3. 3.Best estimate of 36 × 80? (a) 32000 (b) 3200 (c) 320
  4. 4.Best estimate of 488 + 144? (a) 800 (b) 600 (c) 400
  5. 5.Best estimate of 269 + 558? (a) 700 (b) 900 (c) 1100
  6. 6.Best estimate of 76 × 18? (a) 1600 (b) 16000 (c) 160
  7. 7.Best estimate of 27 × 68? (a) 2100 (b) 21000 (c) 210
  8. 8.Best estimate of 17 × 17? (a) 400 (b) 4000 (c) 40
  9. 9.Best estimate of 66 × 72? (a) 4900 (b) 490 (c) 49000
  10. 10.Best estimate of 57 × 31? (a) 1800 (b) 18000 (c) 180
  11. 11.Best estimate of 86 × 57? (a) 540 (b) 5400 (c) 54000
  12. 12.Best estimate of 96 × 52? (a) 50000 (b) 500 (c) 5000
  13. 13.Best estimate of 36 × 78? (a) 32000 (b) 320 (c) 3200
  14. 14.Best estimate of 46 × 53? (a) 2500 (b) 250 (c) 25000
  15. 15.Best estimate of 579 + 700? (a) 1100 (b) 1500 (c) 1300
  16. 16.Best estimate of 50 × 96? (a) 5000 (b) 500 (c) 50000
  17. 17.Best estimate of 217 + 743? (a) 900 (b) 1100 (c) 700
  18. 18.Best estimate of 33 × 72? (a) 2100 (b) 21000 (c) 210
  19. 19.Best estimate of 252 + 704? (a) 1000 (b) 1200 (c) 800
  20. 20.Best estimate of 19 × 96? (a) 200 (b) 2000 (c) 20000
  21. 21.Best estimate of 140 + 449? (a) 500 (b) 700 (c) 300
  22. 22.Best estimate of 26 × 14? (a) 30 (b) 300 (c) 3000
  23. 23.Best estimate of 94 × 14? (a) 9000 (b) 900 (c) 90
  24. 24.Best estimate of 353 + 754? (a) 1000 (b) 1200 (c) 1400
  25. 25.Best estimate of 875 + 146? (a) 1200 (b) 800 (c) 1000
  26. 26.Best estimate of 846 + 865? (a) 1900 (b) 1500 (c) 1700
  27. 27.Best estimate of 16 × 28? (a) 600 (b) 6000 (c) 60
  28. 28.Best estimate of 98 × 79? (a) 800 (b) 8000 (c) 80000
  29. 29.Best estimate of 17 × 18? (a) 40 (b) 4000 (c) 400
  30. 30.Best estimate of 651 + 858? (a) 1800 (b) 1400 (c) 1600
  31. 31.Best estimate of 48 × 86? (a) 4500 (b) 45000 (c) 450
  32. 32.Best estimate of 66 × 16? (a) 1400 (b) 14000 (c) 140
  33. 33.Best estimate of 19 × 18? (a) 4000 (b) 400 (c) 40
  34. 34.Best estimate of 33 × 61? (a) 1800 (b) 180 (c) 18000
  35. 35.Best estimate of 793 + 742? (a) 1300 (b) 1700 (c) 1500
  36. 36.Best estimate of 238 + 688? (a) 700 (b) 1100 (c) 900
  37. 37.Best estimate of 27 × 81? (a) 24000 (b) 2400 (c) 240
  38. 38.Best estimate of 67 × 12? (a) 7000 (b) 700 (c) 70
  39. 39.Best estimate of 54 × 24? (a) 1000 (b) 100 (c) 10000
  40. 40.Best estimate of 738 + 535? (a) 1000 (b) 1200 (c) 1400

Answer key

  1. 800
  2. 1000
  3. 3200
  4. 600
  5. 900
  6. 1600
  7. 2100
  8. 400
  9. 4900
  10. 1800
  11. 5400
  12. 5000
  13. 3200
  14. 2500
  15. 1300
  16. 5000
  17. 900
  18. 2100
  19. 1000
  20. 2000
  21. 500
  22. 300
  23. 900
  24. 1200
  25. 1000
  26. 1700
  27. 600
  28. 8000
  29. 400
  30. 1600
  31. 4500
  32. 1400
  33. 400
  34. 1800
  35. 1500
  36. 900
  37. 2400
  38. 700
  39. 1000
  40. 1200

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