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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 322 · 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 585 + 533? (a) 1100 (b) 1300 (c) 900
  2. 2.Best estimate of 17 × 30? (a) 60 (b) 600 (c) 6000
  3. 3.Best estimate of 73 × 89? (a) 630 (b) 6300 (c) 63000
  4. 4.Best estimate of 353 + 470? (a) 1100 (b) 700 (c) 900
  5. 5.Best estimate of 660 + 379? (a) 1300 (b) 1100 (c) 900
  6. 6.Best estimate of 700 + 607? (a) 1300 (b) 1100 (c) 1500
  7. 7.Best estimate of 26 × 12? (a) 300 (b) 3000 (c) 30
  8. 8.Best estimate of 249 + 837? (a) 1000 (b) 800 (c) 1200
  9. 9.Best estimate of 679 + 600? (a) 1300 (b) 1500 (c) 1100
  10. 10.Best estimate of 206 + 467? (a) 500 (b) 700 (c) 900
  11. 11.Best estimate of 82 × 26? (a) 2400 (b) 24000 (c) 240
  12. 12.Best estimate of 507 + 587? (a) 1100 (b) 1300 (c) 900
  13. 13.Best estimate of 146 + 197? (a) 500 (b) 300 (c) 100
  14. 14.Best estimate of 867 + 565? (a) 1500 (b) 1300 (c) 1700
  15. 15.Best estimate of 215 + 388? (a) 600 (b) 400 (c) 800
  16. 16.Best estimate of 124 + 232? (a) 300 (b) 100 (c) 500
  17. 17.Best estimate of 93 × 84? (a) 72000 (b) 7200 (c) 720
  18. 18.Best estimate of 81 × 56? (a) 480 (b) 48000 (c) 4800
  19. 19.Best estimate of 264 + 234? (a) 700 (b) 300 (c) 500
  20. 20.Best estimate of 229 + 546? (a) 500 (b) 900 (c) 700
  21. 21.Best estimate of 298 + 216? (a) 700 (b) 500 (c) 300
  22. 22.Best estimate of 295 + 745? (a) 800 (b) 1000 (c) 1200
  23. 23.Best estimate of 43 × 78? (a) 3200 (b) 320 (c) 32000
  24. 24.Best estimate of 352 + 474? (a) 700 (b) 900 (c) 1100
  25. 25.Best estimate of 720 + 489? (a) 1200 (b) 1400 (c) 1000
  26. 26.Best estimate of 191 + 311? (a) 700 (b) 300 (c) 500
  27. 27.Best estimate of 89 × 16? (a) 1800 (b) 18000 (c) 180
  28. 28.Best estimate of 98 × 46? (a) 50000 (b) 5000 (c) 500
  29. 29.Best estimate of 82 × 21? (a) 16000 (b) 160 (c) 1600
  30. 30.Best estimate of 437 + 703? (a) 1100 (b) 900 (c) 1300
  31. 31.Best estimate of 199 + 435? (a) 400 (b) 600 (c) 800
  32. 32.Best estimate of 17 × 67? (a) 1400 (b) 14000 (c) 140
  33. 33.Best estimate of 81 × 30? (a) 2400 (b) 240 (c) 24000
  34. 34.Best estimate of 52 × 18? (a) 100 (b) 10000 (c) 1000
  35. 35.Best estimate of 19 × 79? (a) 1600 (b) 16000 (c) 160
  36. 36.Best estimate of 185 + 293? (a) 700 (b) 500 (c) 300
  37. 37.Best estimate of 173 + 128? (a) 100 (b) 300 (c) 500
  38. 38.Best estimate of 16 × 92? (a) 18000 (b) 180 (c) 1800
  39. 39.Best estimate of 313 + 442? (a) 500 (b) 900 (c) 700
  40. 40.Best estimate of 306 + 445? (a) 700 (b) 500 (c) 900

Answer key

  1. 1100
  2. 600
  3. 6300
  4. 900
  5. 1100
  6. 1300
  7. 300
  8. 1000
  9. 1300
  10. 700
  11. 2400
  12. 1100
  13. 300
  14. 1500
  15. 600
  16. 300
  17. 7200
  18. 4800
  19. 500
  20. 700
  21. 500
  22. 1000
  23. 3200
  24. 900
  25. 1200
  26. 500
  27. 1800
  28. 5000
  29. 1600
  30. 1100
  31. 600
  32. 1400
  33. 2400
  34. 1000
  35. 1600
  36. 500
  37. 300
  38. 1800
  39. 700
  40. 700

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