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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 943 · 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 532 + 194? (a) 500 (b) 900 (c) 700
  2. 2.Best estimate of 23 × 14? (a) 2000 (b) 200 (c) 20
  3. 3.Best estimate of 64 × 37? (a) 240 (b) 2400 (c) 24000
  4. 4.Best estimate of 476 + 833? (a) 1300 (b) 1100 (c) 1500
  5. 5.Best estimate of 609 + 267? (a) 900 (b) 1100 (c) 700
  6. 6.Best estimate of 89 × 90? (a) 8100 (b) 81000 (c) 810
  7. 7.Best estimate of 20 × 54? (a) 10000 (b) 1000 (c) 100
  8. 8.Best estimate of 33 × 34? (a) 900 (b) 9000 (c) 90
  9. 9.Best estimate of 30 × 20? (a) 6000 (b) 60 (c) 600
  10. 10.Best estimate of 728 + 578? (a) 1100 (b) 1300 (c) 1500
  11. 11.Best estimate of 489 + 835? (a) 1100 (b) 1300 (c) 1500
  12. 12.Best estimate of 16 × 59? (a) 120 (b) 12000 (c) 1200
  13. 13.Best estimate of 37 × 66? (a) 2800 (b) 28000 (c) 280
  14. 14.Best estimate of 844 + 802? (a) 1600 (b) 1800 (c) 1400
  15. 15.Best estimate of 161 + 167? (a) 200 (b) 400 (c) 600
  16. 16.Best estimate of 84 × 29? (a) 24000 (b) 240 (c) 2400
  17. 17.Best estimate of 20 × 30? (a) 60 (b) 6000 (c) 600
  18. 18.Best estimate of 36 × 68? (a) 280 (b) 2800 (c) 28000
  19. 19.Best estimate of 20 × 12? (a) 200 (b) 2000 (c) 20
  20. 20.Best estimate of 628 + 137? (a) 500 (b) 700 (c) 900
  21. 21.Best estimate of 595 + 455? (a) 1300 (b) 900 (c) 1100
  22. 22.Best estimate of 93 × 90? (a) 8100 (b) 81000 (c) 810
  23. 23.Best estimate of 67 × 16? (a) 1400 (b) 140 (c) 14000
  24. 24.Best estimate of 66 × 13? (a) 70 (b) 7000 (c) 700
  25. 25.Best estimate of 177 + 230? (a) 400 (b) 200 (c) 600
  26. 26.Best estimate of 82 × 87? (a) 7200 (b) 72000 (c) 720
  27. 27.Best estimate of 70 × 14? (a) 7000 (b) 700 (c) 70
  28. 28.Best estimate of 70 × 27? (a) 2100 (b) 21000 (c) 210
  29. 29.Best estimate of 24 × 66? (a) 1400 (b) 14000 (c) 140
  30. 30.Best estimate of 841 + 869? (a) 1700 (b) 1900 (c) 1500
  31. 31.Best estimate of 187 + 614? (a) 600 (b) 800 (c) 1000
  32. 32.Best estimate of 577 + 733? (a) 1500 (b) 1300 (c) 1100
  33. 33.Best estimate of 572 + 238? (a) 800 (b) 1000 (c) 600
  34. 34.Best estimate of 47 × 30? (a) 1500 (b) 150 (c) 15000
  35. 35.Best estimate of 63 × 30? (a) 1800 (b) 18000 (c) 180
  36. 36.Best estimate of 57 × 59? (a) 36000 (b) 3600 (c) 360
  37. 37.Best estimate of 37 × 92? (a) 360 (b) 36000 (c) 3600
  38. 38.Best estimate of 17 × 68? (a) 1400 (b) 140 (c) 14000
  39. 39.Best estimate of 146 + 662? (a) 1000 (b) 600 (c) 800
  40. 40.Best estimate of 393 + 437? (a) 1000 (b) 600 (c) 800

Answer key

  1. 700
  2. 200
  3. 2400
  4. 1300
  5. 900
  6. 8100
  7. 1000
  8. 900
  9. 600
  10. 1300
  11. 1300
  12. 1200
  13. 2800
  14. 1600
  15. 400
  16. 2400
  17. 600
  18. 2800
  19. 200
  20. 700
  21. 1100
  22. 8100
  23. 1400
  24. 700
  25. 400
  26. 7200
  27. 700
  28. 2100
  29. 1400
  30. 1700
  31. 800
  32. 1300
  33. 800
  34. 1500
  35. 1800
  36. 3600
  37. 3600
  38. 1400
  39. 800
  40. 800

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