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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 660 · 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 799 + 217? (a) 1200 (b) 800 (c) 1000
  2. 2.Best estimate of 841 + 279? (a) 1300 (b) 900 (c) 1100
  3. 3.Best estimate of 18 × 40? (a) 80 (b) 800 (c) 8000
  4. 4.Best estimate of 98 × 34? (a) 30000 (b) 3000 (c) 300
  5. 5.Best estimate of 808 + 248? (a) 800 (b) 1200 (c) 1000
  6. 6.Best estimate of 84 × 68? (a) 5600 (b) 56000 (c) 560
  7. 7.Best estimate of 296 + 190? (a) 700 (b) 300 (c) 500
  8. 8.Best estimate of 308 + 279? (a) 600 (b) 800 (c) 400
  9. 9.Best estimate of 31 × 56? (a) 18000 (b) 1800 (c) 180
  10. 10.Best estimate of 12 × 68? (a) 700 (b) 70 (c) 7000
  11. 11.Best estimate of 41 × 32? (a) 120 (b) 1200 (c) 12000
  12. 12.Best estimate of 790 + 311? (a) 1100 (b) 1300 (c) 900
  13. 13.Best estimate of 26 × 46? (a) 15000 (b) 150 (c) 1500
  14. 14.Best estimate of 60 × 29? (a) 18000 (b) 180 (c) 1800
  15. 15.Best estimate of 279 + 400? (a) 900 (b) 500 (c) 700
  16. 16.Best estimate of 63 × 81? (a) 48000 (b) 480 (c) 4800
  17. 17.Best estimate of 86 × 43? (a) 3600 (b) 36000 (c) 360
  18. 18.Best estimate of 36 × 17? (a) 800 (b) 8000 (c) 80
  19. 19.Best estimate of 189 + 189? (a) 600 (b) 200 (c) 400
  20. 20.Best estimate of 98 × 76? (a) 8000 (b) 80000 (c) 800
  21. 21.Best estimate of 69 × 66? (a) 49000 (b) 490 (c) 4900
  22. 22.Best estimate of 61 × 89? (a) 54000 (b) 540 (c) 5400
  23. 23.Best estimate of 712 + 243? (a) 900 (b) 700 (c) 1100
  24. 24.Best estimate of 90 × 89? (a) 81000 (b) 810 (c) 8100
  25. 25.Best estimate of 40 × 94? (a) 360 (b) 3600 (c) 36000
  26. 26.Best estimate of 50 × 67? (a) 350 (b) 3500 (c) 35000
  27. 27.Best estimate of 61 × 59? (a) 36000 (b) 360 (c) 3600
  28. 28.Best estimate of 228 + 164? (a) 400 (b) 600 (c) 200
  29. 29.Best estimate of 89 × 31? (a) 27000 (b) 2700 (c) 270
  30. 30.Best estimate of 24 × 66? (a) 14000 (b) 140 (c) 1400
  31. 31.Best estimate of 168 + 610? (a) 600 (b) 800 (c) 1000
  32. 32.Best estimate of 41 × 83? (a) 32000 (b) 3200 (c) 320
  33. 33.Best estimate of 590 + 735? (a) 1500 (b) 1100 (c) 1300
  34. 34.Best estimate of 33 × 66? (a) 2100 (b) 21000 (c) 210
  35. 35.Best estimate of 127 + 845? (a) 700 (b) 900 (c) 1100
  36. 36.Best estimate of 63 × 48? (a) 30000 (b) 3000 (c) 300
  37. 37.Best estimate of 53 × 83? (a) 40000 (b) 400 (c) 4000
  38. 38.Best estimate of 277 + 258? (a) 600 (b) 800 (c) 400
  39. 39.Best estimate of 80 × 92? (a) 7200 (b) 72000 (c) 720
  40. 40.Best estimate of 16 × 63? (a) 12000 (b) 120 (c) 1200

Answer key

  1. 1000
  2. 1100
  3. 800
  4. 3000
  5. 1000
  6. 5600
  7. 500
  8. 600
  9. 1800
  10. 700
  11. 1200
  12. 1100
  13. 1500
  14. 1800
  15. 700
  16. 4800
  17. 3600
  18. 800
  19. 400
  20. 8000
  21. 4900
  22. 5400
  23. 900
  24. 8100
  25. 3600
  26. 3500
  27. 3600
  28. 400
  29. 2700
  30. 1400
  31. 800
  32. 3200
  33. 1300
  34. 2100
  35. 900
  36. 3000
  37. 4000
  38. 600
  39. 7200
  40. 1200

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