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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 794 · 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 759 + 591? (a) 1400 (b) 1600 (c) 1200
  2. 2.Best estimate of 295 + 513? (a) 600 (b) 800 (c) 1000
  3. 3.Best estimate of 189 + 506? (a) 900 (b) 500 (c) 700
  4. 4.Best estimate of 452 + 307? (a) 800 (b) 600 (c) 1000
  5. 5.Best estimate of 63 × 69? (a) 4200 (b) 42000 (c) 420
  6. 6.Best estimate of 54 × 29? (a) 15000 (b) 150 (c) 1500
  7. 7.Best estimate of 97 × 17? (a) 200 (b) 2000 (c) 20000
  8. 8.Best estimate of 630 + 631? (a) 1000 (b) 1400 (c) 1200
  9. 9.Best estimate of 12 × 56? (a) 6000 (b) 60 (c) 600
  10. 10.Best estimate of 305 + 637? (a) 1100 (b) 700 (c) 900
  11. 11.Best estimate of 326 + 777? (a) 1100 (b) 1300 (c) 900
  12. 12.Best estimate of 70 × 19? (a) 140 (b) 14000 (c) 1400
  13. 13.Best estimate of 136 + 173? (a) 300 (b) 500 (c) 100
  14. 14.Best estimate of 512 + 644? (a) 1300 (b) 1100 (c) 900
  15. 15.Best estimate of 70 × 77? (a) 5600 (b) 560 (c) 56000
  16. 16.Best estimate of 88 × 76? (a) 720 (b) 72000 (c) 7200
  17. 17.Best estimate of 802 + 255? (a) 900 (b) 1300 (c) 1100
  18. 18.Best estimate of 628 + 366? (a) 1200 (b) 1000 (c) 800
  19. 19.Best estimate of 243 + 637? (a) 800 (b) 1000 (c) 600
  20. 20.Best estimate of 861 + 567? (a) 1700 (b) 1500 (c) 1300
  21. 21.Best estimate of 13 × 91? (a) 9000 (b) 900 (c) 90
  22. 22.Best estimate of 306 + 434? (a) 500 (b) 900 (c) 700
  23. 23.Best estimate of 28 × 33? (a) 9000 (b) 90 (c) 900
  24. 24.Best estimate of 71 × 63? (a) 4200 (b) 42000 (c) 420
  25. 25.Best estimate of 23 × 89? (a) 180 (b) 1800 (c) 18000
  26. 26.Best estimate of 56 × 13? (a) 60 (b) 600 (c) 6000
  27. 27.Best estimate of 307 + 490? (a) 600 (b) 800 (c) 1000
  28. 28.Best estimate of 56 × 68? (a) 4200 (b) 42000 (c) 420
  29. 29.Best estimate of 56 × 49? (a) 3000 (b) 30000 (c) 300
  30. 30.Best estimate of 790 + 204? (a) 800 (b) 1000 (c) 1200
  31. 31.Best estimate of 96 × 83? (a) 80000 (b) 8000 (c) 800
  32. 32.Best estimate of 92 × 19? (a) 18000 (b) 180 (c) 1800
  33. 33.Best estimate of 864 + 519? (a) 1600 (b) 1200 (c) 1400
  34. 34.Best estimate of 60 × 87? (a) 540 (b) 54000 (c) 5400
  35. 35.Best estimate of 429 + 145? (a) 500 (b) 300 (c) 700
  36. 36.Best estimate of 432 + 556? (a) 1200 (b) 800 (c) 1000
  37. 37.Best estimate of 661 + 554? (a) 1100 (b) 1300 (c) 1500
  38. 38.Best estimate of 56 × 67? (a) 42000 (b) 4200 (c) 420
  39. 39.Best estimate of 685 + 432? (a) 1300 (b) 900 (c) 1100
  40. 40.Best estimate of 23 × 34? (a) 600 (b) 6000 (c) 60

Answer key

  1. 1400
  2. 800
  3. 700
  4. 800
  5. 4200
  6. 1500
  7. 2000
  8. 1200
  9. 600
  10. 900
  11. 1100
  12. 1400
  13. 300
  14. 1100
  15. 5600
  16. 7200
  17. 1100
  18. 1000
  19. 800
  20. 1500
  21. 900
  22. 700
  23. 900
  24. 4200
  25. 1800
  26. 600
  27. 800
  28. 4200
  29. 3000
  30. 1000
  31. 8000
  32. 1800
  33. 1400
  34. 5400
  35. 500
  36. 1000
  37. 1300
  38. 4200
  39. 1100
  40. 600

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