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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 549 · 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 445 + 336? (a) 500 (b) 700 (c) 900
  2. 2.Best estimate of 78 × 96? (a) 80000 (b) 800 (c) 8000
  3. 3.Best estimate of 93 × 71? (a) 630 (b) 6300 (c) 63000
  4. 4.Best estimate of 29 × 46? (a) 150 (b) 15000 (c) 1500
  5. 5.Best estimate of 824 + 625? (a) 1600 (b) 1200 (c) 1400
  6. 6.Best estimate of 167 + 734? (a) 900 (b) 1100 (c) 700
  7. 7.Best estimate of 39 × 96? (a) 40000 (b) 4000 (c) 400
  8. 8.Best estimate of 52 × 30? (a) 1500 (b) 15000 (c) 150
  9. 9.Best estimate of 879 + 431? (a) 1100 (b) 1300 (c) 1500
  10. 10.Best estimate of 333 + 704? (a) 1000 (b) 1200 (c) 800
  11. 11.Best estimate of 84 × 87? (a) 72000 (b) 720 (c) 7200
  12. 12.Best estimate of 574 + 200? (a) 800 (b) 600 (c) 1000
  13. 13.Best estimate of 866 + 590? (a) 1300 (b) 1700 (c) 1500
  14. 14.Best estimate of 143 + 859? (a) 800 (b) 1000 (c) 1200
  15. 15.Best estimate of 832 + 217? (a) 1000 (b) 800 (c) 1200
  16. 16.Best estimate of 724 + 751? (a) 1500 (b) 1300 (c) 1700
  17. 17.Best estimate of 753 + 302? (a) 1300 (b) 900 (c) 1100
  18. 18.Best estimate of 58 × 74? (a) 4200 (b) 420 (c) 42000
  19. 19.Best estimate of 66 × 94? (a) 6300 (b) 630 (c) 63000
  20. 20.Best estimate of 842 + 185? (a) 1000 (b) 1200 (c) 800
  21. 21.Best estimate of 310 + 164? (a) 700 (b) 500 (c) 300
  22. 22.Best estimate of 62 × 24? (a) 120 (b) 12000 (c) 1200
  23. 23.Best estimate of 13 × 20? (a) 2000 (b) 20 (c) 200
  24. 24.Best estimate of 17 × 30? (a) 600 (b) 6000 (c) 60
  25. 25.Best estimate of 91 × 29? (a) 2700 (b) 270 (c) 27000
  26. 26.Best estimate of 226 + 835? (a) 800 (b) 1000 (c) 1200
  27. 27.Best estimate of 86 × 39? (a) 360 (b) 3600 (c) 36000
  28. 28.Best estimate of 84 × 16? (a) 16000 (b) 1600 (c) 160
  29. 29.Best estimate of 47 × 20? (a) 10000 (b) 1000 (c) 100
  30. 30.Best estimate of 515 + 448? (a) 900 (b) 700 (c) 1100
  31. 31.Best estimate of 728 + 528? (a) 1000 (b) 1400 (c) 1200
  32. 32.Best estimate of 50 × 20? (a) 1000 (b) 100 (c) 10000
  33. 33.Best estimate of 93 × 34? (a) 270 (b) 27000 (c) 2700
  34. 34.Best estimate of 202 + 672? (a) 900 (b) 1100 (c) 700
  35. 35.Best estimate of 208 + 682? (a) 900 (b) 700 (c) 1100
  36. 36.Best estimate of 171 + 446? (a) 800 (b) 400 (c) 600
  37. 37.Best estimate of 96 × 36? (a) 400 (b) 40000 (c) 4000
  38. 38.Best estimate of 454 + 426? (a) 700 (b) 1100 (c) 900
  39. 39.Best estimate of 37 × 97? (a) 4000 (b) 40000 (c) 400
  40. 40.Best estimate of 248 + 296? (a) 500 (b) 300 (c) 700

Answer key

  1. 700
  2. 8000
  3. 6300
  4. 1500
  5. 1400
  6. 900
  7. 4000
  8. 1500
  9. 1300
  10. 1000
  11. 7200
  12. 800
  13. 1500
  14. 1000
  15. 1000
  16. 1500
  17. 1100
  18. 4200
  19. 6300
  20. 1000
  21. 500
  22. 1200
  23. 200
  24. 600
  25. 2700
  26. 1000
  27. 3600
  28. 1600
  29. 1000
  30. 900
  31. 1200
  32. 1000
  33. 2700
  34. 900
  35. 900
  36. 600
  37. 4000
  38. 900
  39. 4000
  40. 500

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