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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 693 · 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 497 + 603? (a) 1300 (b) 900 (c) 1100
  2. 2.Best estimate of 62 × 56? (a) 360 (b) 3600 (c) 36000
  3. 3.Best estimate of 797 + 336? (a) 1300 (b) 900 (c) 1100
  4. 4.Best estimate of 60 × 70? (a) 420 (b) 4200 (c) 42000
  5. 5.Best estimate of 372 + 314? (a) 500 (b) 700 (c) 900
  6. 6.Best estimate of 251 + 742? (a) 1000 (b) 800 (c) 1200
  7. 7.Best estimate of 136 + 557? (a) 900 (b) 500 (c) 700
  8. 8.Best estimate of 815 + 614? (a) 1400 (b) 1200 (c) 1600
  9. 9.Best estimate of 96 × 80? (a) 8000 (b) 80000 (c) 800
  10. 10.Best estimate of 86 × 86? (a) 8100 (b) 81000 (c) 810
  11. 11.Best estimate of 480 + 548? (a) 1000 (b) 800 (c) 1200
  12. 12.Best estimate of 466 + 281? (a) 600 (b) 800 (c) 1000
  13. 13.Best estimate of 81 × 44? (a) 320 (b) 32000 (c) 3200
  14. 14.Best estimate of 136 + 318? (a) 200 (b) 600 (c) 400
  15. 15.Best estimate of 47 × 59? (a) 30000 (b) 3000 (c) 300
  16. 16.Best estimate of 179 + 473? (a) 500 (b) 900 (c) 700
  17. 17.Best estimate of 37 × 76? (a) 320 (b) 32000 (c) 3200
  18. 18.Best estimate of 70 × 42? (a) 280 (b) 2800 (c) 28000
  19. 19.Best estimate of 243 + 185? (a) 400 (b) 600 (c) 200
  20. 20.Best estimate of 91 × 80? (a) 7200 (b) 720 (c) 72000
  21. 21.Best estimate of 808 + 178? (a) 1200 (b) 1000 (c) 800
  22. 22.Best estimate of 56 × 66? (a) 4200 (b) 42000 (c) 420
  23. 23.Best estimate of 26 × 46? (a) 150 (b) 15000 (c) 1500
  24. 24.Best estimate of 51 × 37? (a) 20000 (b) 200 (c) 2000
  25. 25.Best estimate of 29 × 56? (a) 1800 (b) 18000 (c) 180
  26. 26.Best estimate of 88 × 81? (a) 720 (b) 7200 (c) 72000
  27. 27.Best estimate of 838 + 169? (a) 1200 (b) 800 (c) 1000
  28. 28.Best estimate of 156 + 502? (a) 900 (b) 500 (c) 700
  29. 29.Best estimate of 23 × 30? (a) 600 (b) 6000 (c) 60
  30. 30.Best estimate of 724 + 855? (a) 1600 (b) 1400 (c) 1800
  31. 31.Best estimate of 22 × 36? (a) 800 (b) 8000 (c) 80
  32. 32.Best estimate of 549 + 245? (a) 500 (b) 900 (c) 700
  33. 33.Best estimate of 457 + 127? (a) 600 (b) 400 (c) 800
  34. 34.Best estimate of 862 + 713? (a) 1800 (b) 1600 (c) 1400
  35. 35.Best estimate of 41 × 36? (a) 1600 (b) 160 (c) 16000
  36. 36.Best estimate of 51 × 71? (a) 350 (b) 35000 (c) 3500
  37. 37.Best estimate of 328 + 425? (a) 700 (b) 900 (c) 500
  38. 38.Best estimate of 98 × 24? (a) 20000 (b) 2000 (c) 200
  39. 39.Best estimate of 87 × 59? (a) 540 (b) 5400 (c) 54000
  40. 40.Best estimate of 39 × 67? (a) 280 (b) 2800 (c) 28000

Answer key

  1. 1100
  2. 3600
  3. 1100
  4. 4200
  5. 700
  6. 1000
  7. 700
  8. 1400
  9. 8000
  10. 8100
  11. 1000
  12. 800
  13. 3200
  14. 400
  15. 3000
  16. 700
  17. 3200
  18. 2800
  19. 400
  20. 7200
  21. 1000
  22. 4200
  23. 1500
  24. 2000
  25. 1800
  26. 7200
  27. 1000
  28. 700
  29. 600
  30. 1600
  31. 800
  32. 700
  33. 600
  34. 1600
  35. 1600
  36. 3500
  37. 700
  38. 2000
  39. 5400
  40. 2800

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