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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 230 · 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 56 × 89? (a) 54000 (b) 540 (c) 5400
  2. 2.Best estimate of 620 + 511? (a) 900 (b) 1100 (c) 1300
  3. 3.Best estimate of 24 × 64? (a) 12000 (b) 120 (c) 1200
  4. 4.Best estimate of 80 × 22? (a) 16000 (b) 160 (c) 1600
  5. 5.Best estimate of 256 + 343? (a) 400 (b) 600 (c) 800
  6. 6.Best estimate of 854 + 776? (a) 1500 (b) 1900 (c) 1700
  7. 7.Best estimate of 187 + 253? (a) 700 (b) 500 (c) 300
  8. 8.Best estimate of 63 × 32? (a) 18000 (b) 1800 (c) 180
  9. 9.Best estimate of 157 + 706? (a) 700 (b) 1100 (c) 900
  10. 10.Best estimate of 89 × 39? (a) 3600 (b) 36000 (c) 360
  11. 11.Best estimate of 22 × 61? (a) 120 (b) 12000 (c) 1200
  12. 12.Best estimate of 672 + 574? (a) 1300 (b) 1100 (c) 1500
  13. 13.Best estimate of 239 + 661? (a) 700 (b) 900 (c) 1100
  14. 14.Best estimate of 36 × 18? (a) 800 (b) 8000 (c) 80
  15. 15.Best estimate of 28 × 56? (a) 1800 (b) 180 (c) 18000
  16. 16.Best estimate of 530 + 332? (a) 800 (b) 600 (c) 1000
  17. 17.Best estimate of 88 × 12? (a) 9000 (b) 900 (c) 90
  18. 18.Best estimate of 71 × 97? (a) 700 (b) 70000 (c) 7000
  19. 19.Best estimate of 395 + 552? (a) 1000 (b) 1200 (c) 800
  20. 20.Best estimate of 136 + 570? (a) 900 (b) 700 (c) 500
  21. 21.Best estimate of 93 × 28? (a) 2700 (b) 270 (c) 27000
  22. 22.Best estimate of 76 × 47? (a) 4000 (b) 40000 (c) 400
  23. 23.Best estimate of 86 × 18? (a) 1800 (b) 18000 (c) 180
  24. 24.Best estimate of 301 + 224? (a) 700 (b) 300 (c) 500
  25. 25.Best estimate of 49 × 14? (a) 5000 (b) 50 (c) 500
  26. 26.Best estimate of 18 × 86? (a) 18000 (b) 180 (c) 1800
  27. 27.Best estimate of 246 + 215? (a) 400 (b) 600 (c) 200
  28. 28.Best estimate of 33 × 98? (a) 30000 (b) 300 (c) 3000
  29. 29.Best estimate of 33 × 17? (a) 60 (b) 600 (c) 6000
  30. 30.Best estimate of 82 × 29? (a) 240 (b) 2400 (c) 24000
  31. 31.Best estimate of 54 × 17? (a) 100 (b) 10000 (c) 1000
  32. 32.Best estimate of 82 × 81? (a) 64000 (b) 6400 (c) 640
  33. 33.Best estimate of 841 + 855? (a) 1900 (b) 1500 (c) 1700
  34. 34.Best estimate of 223 + 396? (a) 600 (b) 800 (c) 400
  35. 35.Best estimate of 225 + 210? (a) 400 (b) 600 (c) 200
  36. 36.Best estimate of 30 × 76? (a) 240 (b) 24000 (c) 2400
  37. 37.Best estimate of 121 + 674? (a) 1000 (b) 800 (c) 600
  38. 38.Best estimate of 468 + 556? (a) 900 (b) 1100 (c) 1300
  39. 39.Best estimate of 82 × 23? (a) 16000 (b) 160 (c) 1600
  40. 40.Best estimate of 31 × 93? (a) 27000 (b) 270 (c) 2700

Answer key

  1. 5400
  2. 1100
  3. 1200
  4. 1600
  5. 600
  6. 1700
  7. 500
  8. 1800
  9. 900
  10. 3600
  11. 1200
  12. 1300
  13. 900
  14. 800
  15. 1800
  16. 800
  17. 900
  18. 7000
  19. 1000
  20. 700
  21. 2700
  22. 4000
  23. 1800
  24. 500
  25. 500
  26. 1800
  27. 400
  28. 3000
  29. 600
  30. 2400
  31. 1000
  32. 6400
  33. 1700
  34. 600
  35. 400
  36. 2400
  37. 800
  38. 1100
  39. 1600
  40. 2700

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