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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 838 · 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 757 + 526? (a) 1500 (b) 1100 (c) 1300
  2. 2.Best estimate of 32 × 86? (a) 270 (b) 2700 (c) 27000
  3. 3.Best estimate of 571 + 456? (a) 1300 (b) 1100 (c) 900
  4. 4.Best estimate of 74 × 46? (a) 3500 (b) 35000 (c) 350
  5. 5.Best estimate of 96 × 66? (a) 7000 (b) 70000 (c) 700
  6. 6.Best estimate of 76 × 72? (a) 56000 (b) 5600 (c) 560
  7. 7.Best estimate of 36 × 77? (a) 3200 (b) 320 (c) 32000
  8. 8.Best estimate of 779 + 149? (a) 700 (b) 1100 (c) 900
  9. 9.Best estimate of 141 + 242? (a) 500 (b) 100 (c) 300
  10. 10.Best estimate of 76 × 16? (a) 1600 (b) 16000 (c) 160
  11. 11.Best estimate of 31 × 21? (a) 60 (b) 6000 (c) 600
  12. 12.Best estimate of 40 × 98? (a) 40000 (b) 4000 (c) 400
  13. 13.Best estimate of 211 + 154? (a) 600 (b) 200 (c) 400
  14. 14.Best estimate of 586 + 139? (a) 500 (b) 700 (c) 900
  15. 15.Best estimate of 36 × 41? (a) 160 (b) 1600 (c) 16000
  16. 16.Best estimate of 819 + 424? (a) 1200 (b) 1000 (c) 1400
  17. 17.Best estimate of 13 × 33? (a) 3000 (b) 300 (c) 30
  18. 18.Best estimate of 16 × 63? (a) 12000 (b) 120 (c) 1200
  19. 19.Best estimate of 311 + 278? (a) 400 (b) 600 (c) 800
  20. 20.Best estimate of 222 + 647? (a) 1000 (b) 800 (c) 600
  21. 21.Best estimate of 69 × 46? (a) 3500 (b) 35000 (c) 350
  22. 22.Best estimate of 39 × 69? (a) 28000 (b) 280 (c) 2800
  23. 23.Best estimate of 93 × 46? (a) 4500 (b) 45000 (c) 450
  24. 24.Best estimate of 18 × 93? (a) 1800 (b) 180 (c) 18000
  25. 25.Best estimate of 40 × 37? (a) 160 (b) 1600 (c) 16000
  26. 26.Best estimate of 43 × 19? (a) 8000 (b) 80 (c) 800
  27. 27.Best estimate of 582 + 239? (a) 800 (b) 600 (c) 1000
  28. 28.Best estimate of 299 + 545? (a) 1000 (b) 800 (c) 600
  29. 29.Best estimate of 37 × 66? (a) 2800 (b) 28000 (c) 280
  30. 30.Best estimate of 79 × 89? (a) 720 (b) 72000 (c) 7200
  31. 31.Best estimate of 76 × 34? (a) 240 (b) 24000 (c) 2400
  32. 32.Best estimate of 396 + 671? (a) 1300 (b) 900 (c) 1100
  33. 33.Best estimate of 224 + 127? (a) 100 (b) 300 (c) 500
  34. 34.Best estimate of 170 + 736? (a) 700 (b) 1100 (c) 900
  35. 35.Best estimate of 426 + 139? (a) 500 (b) 700 (c) 300
  36. 36.Best estimate of 48 × 26? (a) 15000 (b) 150 (c) 1500
  37. 37.Best estimate of 89 × 13? (a) 900 (b) 9000 (c) 90
  38. 38.Best estimate of 42 × 37? (a) 16000 (b) 1600 (c) 160
  39. 39.Best estimate of 72 × 96? (a) 7000 (b) 70000 (c) 700
  40. 40.Best estimate of 26 × 23? (a) 600 (b) 60 (c) 6000

Answer key

  1. 1300
  2. 2700
  3. 1100
  4. 3500
  5. 7000
  6. 5600
  7. 3200
  8. 900
  9. 300
  10. 1600
  11. 600
  12. 4000
  13. 400
  14. 700
  15. 1600
  16. 1200
  17. 300
  18. 1200
  19. 600
  20. 800
  21. 3500
  22. 2800
  23. 4500
  24. 1800
  25. 1600
  26. 800
  27. 800
  28. 800
  29. 2800
  30. 7200
  31. 2400
  32. 1100
  33. 300
  34. 900
  35. 500
  36. 1500
  37. 900
  38. 1600
  39. 7000
  40. 600

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