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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 591 · 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 131 + 351? (a) 500 (b) 300 (c) 700
  2. 2.Best estimate of 27 × 32? (a) 9000 (b) 90 (c) 900
  3. 3.Best estimate of 33 × 58? (a) 18000 (b) 180 (c) 1800
  4. 4.Best estimate of 52 × 88? (a) 45000 (b) 450 (c) 4500
  5. 5.Best estimate of 56 × 12? (a) 60 (b) 6000 (c) 600
  6. 6.Best estimate of 727 + 172? (a) 1100 (b) 900 (c) 700
  7. 7.Best estimate of 66 × 13? (a) 7000 (b) 70 (c) 700
  8. 8.Best estimate of 278 + 445? (a) 500 (b) 700 (c) 900
  9. 9.Best estimate of 640 + 687? (a) 1100 (b) 1300 (c) 1500
  10. 10.Best estimate of 50 × 70? (a) 3500 (b) 350 (c) 35000
  11. 11.Best estimate of 167 + 208? (a) 200 (b) 400 (c) 600
  12. 12.Best estimate of 558 + 302? (a) 700 (b) 900 (c) 1100
  13. 13.Best estimate of 62 × 41? (a) 240 (b) 24000 (c) 2400
  14. 14.Best estimate of 419 + 380? (a) 600 (b) 800 (c) 1000
  15. 15.Best estimate of 57 × 93? (a) 5400 (b) 54000 (c) 540
  16. 16.Best estimate of 121 + 621? (a) 700 (b) 900 (c) 500
  17. 17.Best estimate of 69 × 26? (a) 21000 (b) 2100 (c) 210
  18. 18.Best estimate of 76 × 68? (a) 5600 (b) 560 (c) 56000
  19. 19.Best estimate of 30 × 64? (a) 18000 (b) 180 (c) 1800
  20. 20.Best estimate of 97 × 28? (a) 30000 (b) 300 (c) 3000
  21. 21.Best estimate of 72 × 39? (a) 2800 (b) 28000 (c) 280
  22. 22.Best estimate of 309 + 294? (a) 600 (b) 800 (c) 400
  23. 23.Best estimate of 56 × 77? (a) 48000 (b) 4800 (c) 480
  24. 24.Best estimate of 29 × 78? (a) 24000 (b) 240 (c) 2400
  25. 25.Best estimate of 59 × 73? (a) 4200 (b) 420 (c) 42000
  26. 26.Best estimate of 16 × 16? (a) 400 (b) 40 (c) 4000
  27. 27.Best estimate of 20 × 43? (a) 8000 (b) 80 (c) 800
  28. 28.Best estimate of 86 × 90? (a) 8100 (b) 81000 (c) 810
  29. 29.Best estimate of 84 × 18? (a) 16000 (b) 1600 (c) 160
  30. 30.Best estimate of 36 × 30? (a) 120 (b) 12000 (c) 1200
  31. 31.Best estimate of 608 + 147? (a) 700 (b) 900 (c) 500
  32. 32.Best estimate of 84 × 26? (a) 24000 (b) 240 (c) 2400
  33. 33.Best estimate of 802 + 479? (a) 1300 (b) 1500 (c) 1100
  34. 34.Best estimate of 33 × 30? (a) 900 (b) 9000 (c) 90
  35. 35.Best estimate of 438 + 741? (a) 1300 (b) 1100 (c) 900
  36. 36.Best estimate of 396 + 778? (a) 1000 (b) 1200 (c) 1400
  37. 37.Best estimate of 812 + 506? (a) 1500 (b) 1300 (c) 1100
  38. 38.Best estimate of 27 × 34? (a) 900 (b) 90 (c) 9000
  39. 39.Best estimate of 28 × 24? (a) 6000 (b) 600 (c) 60
  40. 40.Best estimate of 673 + 515? (a) 1200 (b) 1400 (c) 1000

Answer key

  1. 500
  2. 900
  3. 1800
  4. 4500
  5. 600
  6. 900
  7. 700
  8. 700
  9. 1300
  10. 3500
  11. 400
  12. 900
  13. 2400
  14. 800
  15. 5400
  16. 700
  17. 2100
  18. 5600
  19. 1800
  20. 3000
  21. 2800
  22. 600
  23. 4800
  24. 2400
  25. 4200
  26. 400
  27. 800
  28. 8100
  29. 1600
  30. 1200
  31. 700
  32. 2400
  33. 1300
  34. 900
  35. 1100
  36. 1200
  37. 1300
  38. 900
  39. 600
  40. 1200

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