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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 610 · 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 421 + 724? (a) 1300 (b) 1100 (c) 900
  2. 2.Best estimate of 444 + 227? (a) 800 (b) 400 (c) 600
  3. 3.Best estimate of 156 + 163? (a) 600 (b) 200 (c) 400
  4. 4.Best estimate of 712 + 674? (a) 1200 (b) 1600 (c) 1400
  5. 5.Best estimate of 788 + 503? (a) 1300 (b) 1100 (c) 1500
  6. 6.Best estimate of 732 + 385? (a) 1300 (b) 1100 (c) 900
  7. 7.Best estimate of 66 × 26? (a) 21000 (b) 2100 (c) 210
  8. 8.Best estimate of 635 + 271? (a) 1100 (b) 900 (c) 700
  9. 9.Best estimate of 169 + 336? (a) 300 (b) 700 (c) 500
  10. 10.Best estimate of 64 × 83? (a) 4800 (b) 48000 (c) 480
  11. 11.Best estimate of 70 × 48? (a) 3500 (b) 35000 (c) 350
  12. 12.Best estimate of 305 + 803? (a) 900 (b) 1100 (c) 1300
  13. 13.Best estimate of 147 + 606? (a) 700 (b) 900 (c) 500
  14. 14.Best estimate of 806 + 235? (a) 1200 (b) 1000 (c) 800
  15. 15.Best estimate of 40 × 31? (a) 1200 (b) 12000 (c) 120
  16. 16.Best estimate of 571 + 778? (a) 1200 (b) 1600 (c) 1400
  17. 17.Best estimate of 89 × 26? (a) 27000 (b) 2700 (c) 270
  18. 18.Best estimate of 18 × 22? (a) 400 (b) 40 (c) 4000
  19. 19.Best estimate of 69 × 96? (a) 7000 (b) 700 (c) 70000
  20. 20.Best estimate of 36 × 64? (a) 2400 (b) 240 (c) 24000
  21. 21.Best estimate of 356 + 483? (a) 1100 (b) 900 (c) 700
  22. 22.Best estimate of 723 + 152? (a) 900 (b) 700 (c) 1100
  23. 23.Best estimate of 74 × 43? (a) 280 (b) 28000 (c) 2800
  24. 24.Best estimate of 57 × 48? (a) 30000 (b) 300 (c) 3000
  25. 25.Best estimate of 248 + 720? (a) 700 (b) 900 (c) 1100
  26. 26.Best estimate of 63 × 29? (a) 18000 (b) 180 (c) 1800
  27. 27.Best estimate of 49 × 74? (a) 350 (b) 3500 (c) 35000
  28. 28.Best estimate of 453 + 358? (a) 700 (b) 1100 (c) 900
  29. 29.Best estimate of 22 × 36? (a) 80 (b) 8000 (c) 800
  30. 30.Best estimate of 603 + 466? (a) 900 (b) 1100 (c) 1300
  31. 31.Best estimate of 735 + 758? (a) 1700 (b) 1500 (c) 1300
  32. 32.Best estimate of 97 × 77? (a) 8000 (b) 800 (c) 80000
  33. 33.Best estimate of 87 × 93? (a) 81000 (b) 810 (c) 8100
  34. 34.Best estimate of 767 + 251? (a) 1300 (b) 900 (c) 1100
  35. 35.Best estimate of 59 × 56? (a) 3600 (b) 360 (c) 36000
  36. 36.Best estimate of 88 × 42? (a) 36000 (b) 360 (c) 3600
  37. 37.Best estimate of 66 × 43? (a) 28000 (b) 2800 (c) 280
  38. 38.Best estimate of 408 + 818? (a) 1400 (b) 1200 (c) 1000
  39. 39.Best estimate of 287 + 395? (a) 700 (b) 900 (c) 500
  40. 40.Best estimate of 86 × 28? (a) 270 (b) 2700 (c) 27000

Answer key

  1. 1100
  2. 600
  3. 400
  4. 1400
  5. 1300
  6. 1100
  7. 2100
  8. 900
  9. 500
  10. 4800
  11. 3500
  12. 1100
  13. 700
  14. 1000
  15. 1200
  16. 1400
  17. 2700
  18. 400
  19. 7000
  20. 2400
  21. 900
  22. 900
  23. 2800
  24. 3000
  25. 900
  26. 1800
  27. 3500
  28. 900
  29. 800
  30. 1100
  31. 1500
  32. 8000
  33. 8100
  34. 1100
  35. 3600
  36. 3600
  37. 2800
  38. 1200
  39. 700
  40. 2700

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