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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 895 · 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 518 + 579? (a) 1300 (b) 1100 (c) 900
  2. 2.Best estimate of 30 × 73? (a) 210 (b) 2100 (c) 21000
  3. 3.Best estimate of 17 × 87? (a) 180 (b) 1800 (c) 18000
  4. 4.Best estimate of 38 × 16? (a) 8000 (b) 800 (c) 80
  5. 5.Best estimate of 656 + 431? (a) 1100 (b) 1300 (c) 900
  6. 6.Best estimate of 751 + 233? (a) 1000 (b) 800 (c) 1200
  7. 7.Best estimate of 593 + 354? (a) 1200 (b) 800 (c) 1000
  8. 8.Best estimate of 295 + 560? (a) 700 (b) 1100 (c) 900
  9. 9.Best estimate of 347 + 831? (a) 1100 (b) 900 (c) 1300
  10. 10.Best estimate of 537 + 717? (a) 1400 (b) 1200 (c) 1000
  11. 11.Best estimate of 93 × 39? (a) 360 (b) 36000 (c) 3600
  12. 12.Best estimate of 97 × 22? (a) 200 (b) 20000 (c) 2000
  13. 13.Best estimate of 59 × 86? (a) 54000 (b) 540 (c) 5400
  14. 14.Best estimate of 208 + 672? (a) 1100 (b) 700 (c) 900
  15. 15.Best estimate of 46 × 21? (a) 1000 (b) 100 (c) 10000
  16. 16.Best estimate of 763 + 565? (a) 1600 (b) 1400 (c) 1200
  17. 17.Best estimate of 674 + 751? (a) 1700 (b) 1300 (c) 1500
  18. 18.Best estimate of 305 + 128? (a) 400 (b) 600 (c) 200
  19. 19.Best estimate of 26 × 16? (a) 600 (b) 60 (c) 6000
  20. 20.Best estimate of 127 + 186? (a) 100 (b) 500 (c) 300
  21. 21.Best estimate of 97 × 71? (a) 70000 (b) 700 (c) 7000
  22. 22.Best estimate of 363 + 348? (a) 700 (b) 900 (c) 500
  23. 23.Best estimate of 61 × 26? (a) 180 (b) 1800 (c) 18000
  24. 24.Best estimate of 783 + 212? (a) 800 (b) 1200 (c) 1000
  25. 25.Best estimate of 62 × 50? (a) 30000 (b) 3000 (c) 300
  26. 26.Best estimate of 135 + 262? (a) 600 (b) 400 (c) 200
  27. 27.Best estimate of 50 × 84? (a) 40000 (b) 400 (c) 4000
  28. 28.Best estimate of 728 + 726? (a) 1600 (b) 1200 (c) 1400
  29. 29.Best estimate of 552 + 151? (a) 800 (b) 600 (c) 1000
  30. 30.Best estimate of 92 × 29? (a) 27000 (b) 2700 (c) 270
  31. 31.Best estimate of 187 + 224? (a) 600 (b) 400 (c) 200
  32. 32.Best estimate of 203 + 341? (a) 700 (b) 300 (c) 500
  33. 33.Best estimate of 84 × 28? (a) 2400 (b) 240 (c) 24000
  34. 34.Best estimate of 22 × 66? (a) 1400 (b) 14000 (c) 140
  35. 35.Best estimate of 161 + 259? (a) 300 (b) 700 (c) 500
  36. 36.Best estimate of 13 × 69? (a) 700 (b) 7000 (c) 70
  37. 37.Best estimate of 80 × 66? (a) 560 (b) 5600 (c) 56000
  38. 38.Best estimate of 79 × 84? (a) 640 (b) 64000 (c) 6400
  39. 39.Best estimate of 91 × 73? (a) 63000 (b) 630 (c) 6300
  40. 40.Best estimate of 24 × 58? (a) 120 (b) 1200 (c) 12000

Answer key

  1. 1100
  2. 2100
  3. 1800
  4. 800
  5. 1100
  6. 1000
  7. 1000
  8. 900
  9. 1100
  10. 1200
  11. 3600
  12. 2000
  13. 5400
  14. 900
  15. 1000
  16. 1400
  17. 1500
  18. 400
  19. 600
  20. 300
  21. 7000
  22. 700
  23. 1800
  24. 1000
  25. 3000
  26. 400
  27. 4000
  28. 1400
  29. 800
  30. 2700
  31. 400
  32. 500
  33. 2400
  34. 1400
  35. 500
  36. 700
  37. 5600
  38. 6400
  39. 6300
  40. 1200

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