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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 772 · 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 64 × 66? (a) 4200 (b) 42000 (c) 420
  2. 2.Best estimate of 145 + 230? (a) 100 (b) 300 (c) 500
  3. 3.Best estimate of 597 + 705? (a) 1300 (b) 1500 (c) 1100
  4. 4.Best estimate of 98 × 14? (a) 1000 (b) 10000 (c) 100
  5. 5.Best estimate of 48 × 67? (a) 35000 (b) 3500 (c) 350
  6. 6.Best estimate of 22 × 13? (a) 200 (b) 20 (c) 2000
  7. 7.Best estimate of 46 × 34? (a) 150 (b) 15000 (c) 1500
  8. 8.Best estimate of 92 × 62? (a) 54000 (b) 540 (c) 5400
  9. 9.Best estimate of 834 + 204? (a) 1000 (b) 1200 (c) 800
  10. 10.Best estimate of 570 + 152? (a) 800 (b) 600 (c) 1000
  11. 11.Best estimate of 24 × 12? (a) 200 (b) 20 (c) 2000
  12. 12.Best estimate of 141 + 785? (a) 900 (b) 1100 (c) 700
  13. 13.Best estimate of 285 + 651? (a) 1000 (b) 800 (c) 1200
  14. 14.Best estimate of 96 × 34? (a) 300 (b) 30000 (c) 3000
  15. 15.Best estimate of 40 × 56? (a) 24000 (b) 2400 (c) 240
  16. 16.Best estimate of 751 + 653? (a) 1300 (b) 1500 (c) 1700
  17. 17.Best estimate of 22 × 37? (a) 80 (b) 800 (c) 8000
  18. 18.Best estimate of 96 × 74? (a) 7000 (b) 70000 (c) 700
  19. 19.Best estimate of 567 + 480? (a) 1100 (b) 1300 (c) 900
  20. 20.Best estimate of 737 + 426? (a) 900 (b) 1300 (c) 1100
  21. 21.Best estimate of 16 × 73? (a) 14000 (b) 140 (c) 1400
  22. 22.Best estimate of 323 + 679? (a) 1000 (b) 1200 (c) 800
  23. 23.Best estimate of 156 + 469? (a) 500 (b) 900 (c) 700
  24. 24.Best estimate of 80 × 26? (a) 2400 (b) 24000 (c) 240
  25. 25.Best estimate of 26 × 76? (a) 240 (b) 2400 (c) 24000
  26. 26.Best estimate of 46 × 79? (a) 40000 (b) 4000 (c) 400
  27. 27.Best estimate of 32 × 21? (a) 600 (b) 60 (c) 6000
  28. 28.Best estimate of 17 × 40? (a) 8000 (b) 800 (c) 80
  29. 29.Best estimate of 125 + 748? (a) 800 (b) 1000 (c) 600
  30. 30.Best estimate of 790 + 246? (a) 1200 (b) 1000 (c) 800
  31. 31.Best estimate of 654 + 274? (a) 1000 (b) 1200 (c) 800
  32. 32.Best estimate of 592 + 681? (a) 1300 (b) 1500 (c) 1100
  33. 33.Best estimate of 42 × 31? (a) 12000 (b) 1200 (c) 120
  34. 34.Best estimate of 196 + 340? (a) 300 (b) 700 (c) 500
  35. 35.Best estimate of 46 × 73? (a) 35000 (b) 3500 (c) 350
  36. 36.Best estimate of 61 × 40? (a) 24000 (b) 240 (c) 2400
  37. 37.Best estimate of 296 + 413? (a) 700 (b) 500 (c) 900
  38. 38.Best estimate of 64 × 83? (a) 480 (b) 4800 (c) 48000
  39. 39.Best estimate of 360 + 143? (a) 500 (b) 300 (c) 700
  40. 40.Best estimate of 480 + 744? (a) 1000 (b) 1200 (c) 1400

Answer key

  1. 4200
  2. 300
  3. 1300
  4. 1000
  5. 3500
  6. 200
  7. 1500
  8. 5400
  9. 1000
  10. 800
  11. 200
  12. 900
  13. 1000
  14. 3000
  15. 2400
  16. 1500
  17. 800
  18. 7000
  19. 1100
  20. 1100
  21. 1400
  22. 1000
  23. 700
  24. 2400
  25. 2400
  26. 4000
  27. 600
  28. 800
  29. 800
  30. 1000
  31. 1000
  32. 1300
  33. 1200
  34. 500
  35. 3500
  36. 2400
  37. 700
  38. 4800
  39. 500
  40. 1200

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