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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 26 · 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 67 × 84? (a) 560 (b) 56000 (c) 5600
  2. 2.Best estimate of 93 × 14? (a) 90 (b) 9000 (c) 900
  3. 3.Best estimate of 77 × 86? (a) 7200 (b) 72000 (c) 720
  4. 4.Best estimate of 506 + 645? (a) 1300 (b) 1100 (c) 900
  5. 5.Best estimate of 781 + 337? (a) 900 (b) 1100 (c) 1300
  6. 6.Best estimate of 91 × 92? (a) 810 (b) 8100 (c) 81000
  7. 7.Best estimate of 38 × 27? (a) 120 (b) 12000 (c) 1200
  8. 8.Best estimate of 92 × 34? (a) 2700 (b) 270 (c) 27000
  9. 9.Best estimate of 548 + 183? (a) 900 (b) 500 (c) 700
  10. 10.Best estimate of 72 × 12? (a) 70 (b) 7000 (c) 700
  11. 11.Best estimate of 91 × 76? (a) 7200 (b) 720 (c) 72000
  12. 12.Best estimate of 12 × 26? (a) 3000 (b) 30 (c) 300
  13. 13.Best estimate of 41 × 51? (a) 2000 (b) 200 (c) 20000
  14. 14.Best estimate of 317 + 221? (a) 700 (b) 300 (c) 500
  15. 15.Best estimate of 240 + 201? (a) 400 (b) 200 (c) 600
  16. 16.Best estimate of 598 + 622? (a) 1000 (b) 1200 (c) 1400
  17. 17.Best estimate of 629 + 341? (a) 700 (b) 1100 (c) 900
  18. 18.Best estimate of 12 × 91? (a) 90 (b) 900 (c) 9000
  19. 19.Best estimate of 234 + 838? (a) 800 (b) 1200 (c) 1000
  20. 20.Best estimate of 70 × 28? (a) 21000 (b) 210 (c) 2100
  21. 21.Best estimate of 44 × 48? (a) 200 (b) 20000 (c) 2000
  22. 22.Best estimate of 27 × 81? (a) 24000 (b) 240 (c) 2400
  23. 23.Best estimate of 304 + 769? (a) 900 (b) 1300 (c) 1100
  24. 24.Best estimate of 44 × 68? (a) 2800 (b) 28000 (c) 280
  25. 25.Best estimate of 657 + 143? (a) 800 (b) 600 (c) 1000
  26. 26.Best estimate of 180 + 720? (a) 1100 (b) 700 (c) 900
  27. 27.Best estimate of 495 + 304? (a) 600 (b) 1000 (c) 800
  28. 28.Best estimate of 33 × 19? (a) 600 (b) 6000 (c) 60
  29. 29.Best estimate of 602 + 541? (a) 1300 (b) 900 (c) 1100
  30. 30.Best estimate of 245 + 258? (a) 700 (b) 300 (c) 500
  31. 31.Best estimate of 51 × 96? (a) 5000 (b) 500 (c) 50000
  32. 32.Best estimate of 476 + 662? (a) 1200 (b) 1400 (c) 1000
  33. 33.Best estimate of 495 + 777? (a) 1100 (b) 1300 (c) 1500
  34. 34.Best estimate of 13 × 40? (a) 40 (b) 400 (c) 4000
  35. 35.Best estimate of 40 × 86? (a) 36000 (b) 3600 (c) 360
  36. 36.Best estimate of 71 × 96? (a) 7000 (b) 700 (c) 70000
  37. 37.Best estimate of 355 + 630? (a) 1000 (b) 1200 (c) 800
  38. 38.Best estimate of 54 × 56? (a) 30000 (b) 300 (c) 3000
  39. 39.Best estimate of 742 + 226? (a) 900 (b) 1100 (c) 700
  40. 40.Best estimate of 13 × 67? (a) 70 (b) 700 (c) 7000

Answer key

  1. 5600
  2. 900
  3. 7200
  4. 1100
  5. 1100
  6. 8100
  7. 1200
  8. 2700
  9. 700
  10. 700
  11. 7200
  12. 300
  13. 2000
  14. 500
  15. 400
  16. 1200
  17. 900
  18. 900
  19. 1000
  20. 2100
  21. 2000
  22. 2400
  23. 1100
  24. 2800
  25. 800
  26. 900
  27. 800
  28. 600
  29. 1100
  30. 500
  31. 5000
  32. 1200
  33. 1300
  34. 400
  35. 3600
  36. 7000
  37. 1000
  38. 3000
  39. 900
  40. 700

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