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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 401 · 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 663 + 806? (a) 1300 (b) 1700 (c) 1500
  2. 2.Best estimate of 20 × 53? (a) 100 (b) 1000 (c) 10000
  3. 3.Best estimate of 323 + 135? (a) 400 (b) 200 (c) 600
  4. 4.Best estimate of 92 × 26? (a) 2700 (b) 270 (c) 27000
  5. 5.Best estimate of 19 × 56? (a) 120 (b) 12000 (c) 1200
  6. 6.Best estimate of 13 × 93? (a) 900 (b) 90 (c) 9000
  7. 7.Best estimate of 771 + 195? (a) 800 (b) 1200 (c) 1000
  8. 8.Best estimate of 22 × 87? (a) 180 (b) 1800 (c) 18000
  9. 9.Best estimate of 79 × 87? (a) 7200 (b) 72000 (c) 720
  10. 10.Best estimate of 79 × 84? (a) 64000 (b) 640 (c) 6400
  11. 11.Best estimate of 97 × 46? (a) 500 (b) 50000 (c) 5000
  12. 12.Best estimate of 379 + 125? (a) 300 (b) 700 (c) 500
  13. 13.Best estimate of 94 × 23? (a) 18000 (b) 180 (c) 1800
  14. 14.Best estimate of 322 + 352? (a) 900 (b) 500 (c) 700
  15. 15.Best estimate of 57 × 66? (a) 420 (b) 42000 (c) 4200
  16. 16.Best estimate of 28 × 93? (a) 27000 (b) 270 (c) 2700
  17. 17.Best estimate of 16 × 74? (a) 140 (b) 1400 (c) 14000
  18. 18.Best estimate of 595 + 130? (a) 700 (b) 900 (c) 500
  19. 19.Best estimate of 33 × 78? (a) 240 (b) 24000 (c) 2400
  20. 20.Best estimate of 824 + 172? (a) 1200 (b) 800 (c) 1000
  21. 21.Best estimate of 156 + 330? (a) 300 (b) 700 (c) 500
  22. 22.Best estimate of 261 + 225? (a) 500 (b) 300 (c) 700
  23. 23.Best estimate of 12 × 43? (a) 4000 (b) 40 (c) 400
  24. 24.Best estimate of 63 × 84? (a) 4800 (b) 480 (c) 48000
  25. 25.Best estimate of 859 + 327? (a) 1200 (b) 1400 (c) 1000
  26. 26.Best estimate of 56 × 48? (a) 3000 (b) 300 (c) 30000
  27. 27.Best estimate of 28 × 71? (a) 21000 (b) 210 (c) 2100
  28. 28.Best estimate of 16 × 40? (a) 8000 (b) 800 (c) 80
  29. 29.Best estimate of 41 × 47? (a) 200 (b) 20000 (c) 2000
  30. 30.Best estimate of 779 + 277? (a) 900 (b) 1300 (c) 1100
  31. 31.Best estimate of 505 + 161? (a) 500 (b) 700 (c) 900
  32. 32.Best estimate of 749 + 265? (a) 1000 (b) 800 (c) 1200
  33. 33.Best estimate of 39 × 94? (a) 360 (b) 36000 (c) 3600
  34. 34.Best estimate of 91 × 89? (a) 81000 (b) 810 (c) 8100
  35. 35.Best estimate of 43 × 16? (a) 8000 (b) 800 (c) 80
  36. 36.Best estimate of 713 + 198? (a) 1100 (b) 700 (c) 900
  37. 37.Best estimate of 98 × 78? (a) 8000 (b) 80000 (c) 800
  38. 38.Best estimate of 78 × 26? (a) 2400 (b) 240 (c) 24000
  39. 39.Best estimate of 62 × 76? (a) 48000 (b) 4800 (c) 480
  40. 40.Best estimate of 699 + 709? (a) 1200 (b) 1600 (c) 1400

Answer key

  1. 1500
  2. 1000
  3. 400
  4. 2700
  5. 1200
  6. 900
  7. 1000
  8. 1800
  9. 7200
  10. 6400
  11. 5000
  12. 500
  13. 1800
  14. 700
  15. 4200
  16. 2700
  17. 1400
  18. 700
  19. 2400
  20. 1000
  21. 500
  22. 500
  23. 400
  24. 4800
  25. 1200
  26. 3000
  27. 2100
  28. 800
  29. 2000
  30. 1100
  31. 700
  32. 1000
  33. 3600
  34. 8100
  35. 800
  36. 900
  37. 8000
  38. 2400
  39. 4800
  40. 1400

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