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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 560 · 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 77 × 31? (a) 24000 (b) 2400 (c) 240
  2. 2.Best estimate of 39 × 48? (a) 200 (b) 2000 (c) 20000
  3. 3.Best estimate of 264 + 330? (a) 400 (b) 800 (c) 600
  4. 4.Best estimate of 23 × 62? (a) 120 (b) 12000 (c) 1200
  5. 5.Best estimate of 188 + 789? (a) 1000 (b) 1200 (c) 800
  6. 6.Best estimate of 34 × 26? (a) 900 (b) 90 (c) 9000
  7. 7.Best estimate of 420 + 154? (a) 400 (b) 800 (c) 600
  8. 8.Best estimate of 325 + 842? (a) 1100 (b) 900 (c) 1300
  9. 9.Best estimate of 735 + 464? (a) 1200 (b) 1000 (c) 1400
  10. 10.Best estimate of 60 × 30? (a) 1800 (b) 18000 (c) 180
  11. 11.Best estimate of 789 + 412? (a) 1200 (b) 1000 (c) 1400
  12. 12.Best estimate of 685 + 605? (a) 1300 (b) 1500 (c) 1100
  13. 13.Best estimate of 43 × 48? (a) 2000 (b) 200 (c) 20000
  14. 14.Best estimate of 37 × 21? (a) 800 (b) 80 (c) 8000
  15. 15.Best estimate of 795 + 447? (a) 1000 (b) 1200 (c) 1400
  16. 16.Best estimate of 209 + 691? (a) 900 (b) 1100 (c) 700
  17. 17.Best estimate of 43 × 56? (a) 240 (b) 24000 (c) 2400
  18. 18.Best estimate of 37 × 29? (a) 1200 (b) 12000 (c) 120
  19. 19.Best estimate of 824 + 697? (a) 1700 (b) 1500 (c) 1300
  20. 20.Best estimate of 96 × 83? (a) 8000 (b) 800 (c) 80000
  21. 21.Best estimate of 174 + 162? (a) 600 (b) 200 (c) 400
  22. 22.Best estimate of 485 + 837? (a) 1300 (b) 1500 (c) 1100
  23. 23.Best estimate of 741 + 301? (a) 1200 (b) 1000 (c) 800
  24. 24.Best estimate of 867 + 351? (a) 1500 (b) 1100 (c) 1300
  25. 25.Best estimate of 86 × 86? (a) 8100 (b) 81000 (c) 810
  26. 26.Best estimate of 41 × 66? (a) 280 (b) 2800 (c) 28000
  27. 27.Best estimate of 659 + 640? (a) 1300 (b) 1100 (c) 1500
  28. 28.Best estimate of 72 × 13? (a) 70 (b) 700 (c) 7000
  29. 29.Best estimate of 734 + 503? (a) 1400 (b) 1000 (c) 1200
  30. 30.Best estimate of 13 × 91? (a) 9000 (b) 900 (c) 90
  31. 31.Best estimate of 21 × 86? (a) 180 (b) 18000 (c) 1800
  32. 32.Best estimate of 604 + 277? (a) 900 (b) 1100 (c) 700
  33. 33.Best estimate of 72 × 19? (a) 14000 (b) 1400 (c) 140
  34. 34.Best estimate of 140 + 666? (a) 600 (b) 1000 (c) 800
  35. 35.Best estimate of 24 × 20? (a) 400 (b) 4000 (c) 40
  36. 36.Best estimate of 29 × 12? (a) 30 (b) 300 (c) 3000
  37. 37.Best estimate of 548 + 662? (a) 1000 (b) 1400 (c) 1200
  38. 38.Best estimate of 152 + 711? (a) 700 (b) 1100 (c) 900
  39. 39.Best estimate of 67 × 84? (a) 5600 (b) 56000 (c) 560
  40. 40.Best estimate of 710 + 732? (a) 1600 (b) 1400 (c) 1200

Answer key

  1. 2400
  2. 2000
  3. 600
  4. 1200
  5. 1000
  6. 900
  7. 600
  8. 1100
  9. 1200
  10. 1800
  11. 1200
  12. 1300
  13. 2000
  14. 800
  15. 1200
  16. 900
  17. 2400
  18. 1200
  19. 1500
  20. 8000
  21. 400
  22. 1300
  23. 1000
  24. 1300
  25. 8100
  26. 2800
  27. 1300
  28. 700
  29. 1200
  30. 900
  31. 1800
  32. 900
  33. 1400
  34. 800
  35. 400
  36. 300
  37. 1200
  38. 900
  39. 5600
  40. 1400

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