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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 492 · 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 12 × 27? (a) 30 (b) 300 (c) 3000
  2. 2.Best estimate of 642 + 360? (a) 1200 (b) 1000 (c) 800
  3. 3.Best estimate of 467 + 343? (a) 800 (b) 1000 (c) 600
  4. 4.Best estimate of 86 × 41? (a) 360 (b) 36000 (c) 3600
  5. 5.Best estimate of 752 + 130? (a) 1100 (b) 900 (c) 700
  6. 6.Best estimate of 23 × 88? (a) 180 (b) 1800 (c) 18000
  7. 7.Best estimate of 183 + 823? (a) 800 (b) 1200 (c) 1000
  8. 8.Best estimate of 48 × 73? (a) 35000 (b) 350 (c) 3500
  9. 9.Best estimate of 98 × 60? (a) 6000 (b) 60000 (c) 600
  10. 10.Best estimate of 92 × 31? (a) 2700 (b) 270 (c) 27000
  11. 11.Best estimate of 47 × 16? (a) 10000 (b) 100 (c) 1000
  12. 12.Best estimate of 63 × 21? (a) 12000 (b) 1200 (c) 120
  13. 13.Best estimate of 178 + 860? (a) 1300 (b) 900 (c) 1100
  14. 14.Best estimate of 229 + 759? (a) 1200 (b) 800 (c) 1000
  15. 15.Best estimate of 286 + 244? (a) 700 (b) 500 (c) 300
  16. 16.Best estimate of 98 × 14? (a) 1000 (b) 100 (c) 10000
  17. 17.Best estimate of 688 + 772? (a) 1500 (b) 1300 (c) 1700
  18. 18.Best estimate of 591 + 498? (a) 1300 (b) 900 (c) 1100
  19. 19.Best estimate of 41 × 48? (a) 2000 (b) 20000 (c) 200
  20. 20.Best estimate of 28 × 91? (a) 2700 (b) 27000 (c) 270
  21. 21.Best estimate of 613 + 647? (a) 1000 (b) 1400 (c) 1200
  22. 22.Best estimate of 79 × 97? (a) 8000 (b) 80000 (c) 800
  23. 23.Best estimate of 38 × 46? (a) 20000 (b) 2000 (c) 200
  24. 24.Best estimate of 39 × 53? (a) 200 (b) 20000 (c) 2000
  25. 25.Best estimate of 133 + 398? (a) 700 (b) 300 (c) 500
  26. 26.Best estimate of 430 + 511? (a) 1100 (b) 700 (c) 900
  27. 27.Best estimate of 16 × 26? (a) 600 (b) 6000 (c) 60
  28. 28.Best estimate of 73 × 32? (a) 2100 (b) 21000 (c) 210
  29. 29.Best estimate of 782 + 135? (a) 900 (b) 1100 (c) 700
  30. 30.Best estimate of 92 × 89? (a) 810 (b) 8100 (c) 81000
  31. 31.Best estimate of 48 × 44? (a) 200 (b) 2000 (c) 20000
  32. 32.Best estimate of 807 + 233? (a) 1000 (b) 800 (c) 1200
  33. 33.Best estimate of 440 + 473? (a) 700 (b) 900 (c) 1100
  34. 34.Best estimate of 800 + 170? (a) 800 (b) 1000 (c) 1200
  35. 35.Best estimate of 334 + 779? (a) 1300 (b) 1100 (c) 900
  36. 36.Best estimate of 548 + 217? (a) 900 (b) 500 (c) 700
  37. 37.Best estimate of 805 + 142? (a) 900 (b) 1100 (c) 700
  38. 38.Best estimate of 56 × 83? (a) 48000 (b) 480 (c) 4800
  39. 39.Best estimate of 77 × 27? (a) 2400 (b) 24000 (c) 240
  40. 40.Best estimate of 694 + 729? (a) 1200 (b) 1400 (c) 1600

Answer key

  1. 300
  2. 1000
  3. 800
  4. 3600
  5. 900
  6. 1800
  7. 1000
  8. 3500
  9. 6000
  10. 2700
  11. 1000
  12. 1200
  13. 1100
  14. 1000
  15. 500
  16. 1000
  17. 1500
  18. 1100
  19. 2000
  20. 2700
  21. 1200
  22. 8000
  23. 2000
  24. 2000
  25. 500
  26. 900
  27. 600
  28. 2100
  29. 900
  30. 8100
  31. 2000
  32. 1000
  33. 900
  34. 1000
  35. 1100
  36. 700
  37. 900
  38. 4800
  39. 2400
  40. 1400

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