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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 522 · 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 36 × 34? (a) 120 (b) 12000 (c) 1200
  2. 2.Best estimate of 159 + 445? (a) 400 (b) 800 (c) 600
  3. 3.Best estimate of 87 × 48? (a) 450 (b) 45000 (c) 4500
  4. 4.Best estimate of 627 + 570? (a) 1000 (b) 1400 (c) 1200
  5. 5.Best estimate of 231 + 322? (a) 300 (b) 500 (c) 700
  6. 6.Best estimate of 30 × 53? (a) 150 (b) 1500 (c) 15000
  7. 7.Best estimate of 61 × 84? (a) 48000 (b) 480 (c) 4800
  8. 8.Best estimate of 66 × 17? (a) 1400 (b) 14000 (c) 140
  9. 9.Best estimate of 73 × 31? (a) 21000 (b) 210 (c) 2100
  10. 10.Best estimate of 172 + 565? (a) 600 (b) 1000 (c) 800
  11. 11.Best estimate of 297 + 448? (a) 900 (b) 500 (c) 700
  12. 12.Best estimate of 86 × 16? (a) 18000 (b) 180 (c) 1800
  13. 13.Best estimate of 642 + 208? (a) 600 (b) 800 (c) 1000
  14. 14.Best estimate of 318 + 537? (a) 800 (b) 600 (c) 1000
  15. 15.Best estimate of 64 × 16? (a) 12000 (b) 120 (c) 1200
  16. 16.Best estimate of 28 × 67? (a) 210 (b) 2100 (c) 21000
  17. 17.Best estimate of 810 + 655? (a) 1700 (b) 1300 (c) 1500
  18. 18.Best estimate of 547 + 807? (a) 1100 (b) 1300 (c) 1500
  19. 19.Best estimate of 14 × 93? (a) 90 (b) 900 (c) 9000
  20. 20.Best estimate of 69 × 96? (a) 70000 (b) 700 (c) 7000
  21. 21.Best estimate of 715 + 226? (a) 700 (b) 900 (c) 1100
  22. 22.Best estimate of 246 + 831? (a) 1200 (b) 800 (c) 1000
  23. 23.Best estimate of 779 + 781? (a) 1800 (b) 1600 (c) 1400
  24. 24.Best estimate of 219 + 284? (a) 500 (b) 700 (c) 300
  25. 25.Best estimate of 560 + 539? (a) 900 (b) 1300 (c) 1100
  26. 26.Best estimate of 133 + 510? (a) 600 (b) 400 (c) 800
  27. 27.Best estimate of 93 × 60? (a) 540 (b) 54000 (c) 5400
  28. 28.Best estimate of 195 + 674? (a) 1100 (b) 700 (c) 900
  29. 29.Best estimate of 58 × 92? (a) 54000 (b) 5400 (c) 540
  30. 30.Best estimate of 62 × 41? (a) 2400 (b) 24000 (c) 240
  31. 31.Best estimate of 757 + 852? (a) 1900 (b) 1500 (c) 1700
  32. 32.Best estimate of 48 × 42? (a) 20000 (b) 2000 (c) 200
  33. 33.Best estimate of 28 × 46? (a) 1500 (b) 150 (c) 15000
  34. 34.Best estimate of 90 × 29? (a) 2700 (b) 270 (c) 27000
  35. 35.Best estimate of 772 + 125? (a) 1100 (b) 700 (c) 900
  36. 36.Best estimate of 407 + 254? (a) 700 (b) 900 (c) 500
  37. 37.Best estimate of 189 + 555? (a) 800 (b) 600 (c) 1000
  38. 38.Best estimate of 27 × 39? (a) 1200 (b) 120 (c) 12000
  39. 39.Best estimate of 501 + 821? (a) 1100 (b) 1300 (c) 1500
  40. 40.Best estimate of 87 × 80? (a) 72000 (b) 720 (c) 7200

Answer key

  1. 1200
  2. 600
  3. 4500
  4. 1200
  5. 500
  6. 1500
  7. 4800
  8. 1400
  9. 2100
  10. 800
  11. 700
  12. 1800
  13. 800
  14. 800
  15. 1200
  16. 2100
  17. 1500
  18. 1300
  19. 900
  20. 7000
  21. 900
  22. 1000
  23. 1600
  24. 500
  25. 1100
  26. 600
  27. 5400
  28. 900
  29. 5400
  30. 2400
  31. 1700
  32. 2000
  33. 1500
  34. 2700
  35. 900
  36. 700
  37. 800
  38. 1200
  39. 1300
  40. 7200

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