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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 507 · 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 23 × 90? (a) 18000 (b) 180 (c) 1800
  2. 2.Best estimate of 27 × 96? (a) 3000 (b) 30000 (c) 300
  3. 3.Best estimate of 62 × 62? (a) 36000 (b) 360 (c) 3600
  4. 4.Best estimate of 225 + 260? (a) 500 (b) 700 (c) 300
  5. 5.Best estimate of 220 + 222? (a) 400 (b) 200 (c) 600
  6. 6.Best estimate of 52 × 74? (a) 35000 (b) 3500 (c) 350
  7. 7.Best estimate of 87 × 66? (a) 6300 (b) 63000 (c) 630
  8. 8.Best estimate of 33 × 39? (a) 12000 (b) 1200 (c) 120
  9. 9.Best estimate of 21 × 73? (a) 1400 (b) 14000 (c) 140
  10. 10.Best estimate of 389 + 237? (a) 800 (b) 600 (c) 400
  11. 11.Best estimate of 461 + 731? (a) 1400 (b) 1000 (c) 1200
  12. 12.Best estimate of 630 + 510? (a) 900 (b) 1100 (c) 1300
  13. 13.Best estimate of 21 × 38? (a) 800 (b) 80 (c) 8000
  14. 14.Best estimate of 53 × 97? (a) 5000 (b) 50000 (c) 500
  15. 15.Best estimate of 36 × 36? (a) 1600 (b) 160 (c) 16000
  16. 16.Best estimate of 285 + 558? (a) 900 (b) 700 (c) 1100
  17. 17.Best estimate of 16 × 12? (a) 2000 (b) 20 (c) 200
  18. 18.Best estimate of 89 × 14? (a) 900 (b) 9000 (c) 90
  19. 19.Best estimate of 843 + 656? (a) 1300 (b) 1500 (c) 1700
  20. 20.Best estimate of 300 + 538? (a) 600 (b) 1000 (c) 800
  21. 21.Best estimate of 763 + 157? (a) 1000 (b) 1200 (c) 800
  22. 22.Best estimate of 629 + 351? (a) 1200 (b) 1000 (c) 800
  23. 23.Best estimate of 56 × 68? (a) 4200 (b) 42000 (c) 420
  24. 24.Best estimate of 56 × 51? (a) 300 (b) 30000 (c) 3000
  25. 25.Best estimate of 544 + 146? (a) 600 (b) 400 (c) 800
  26. 26.Best estimate of 685 + 551? (a) 1500 (b) 1100 (c) 1300
  27. 27.Best estimate of 591 + 338? (a) 900 (b) 1100 (c) 700
  28. 28.Best estimate of 701 + 307? (a) 1200 (b) 800 (c) 1000
  29. 29.Best estimate of 233 + 322? (a) 700 (b) 300 (c) 500
  30. 30.Best estimate of 662 + 242? (a) 1100 (b) 900 (c) 700
  31. 31.Best estimate of 129 + 249? (a) 300 (b) 100 (c) 500
  32. 32.Best estimate of 280 + 194? (a) 700 (b) 500 (c) 300
  33. 33.Best estimate of 67 × 29? (a) 21000 (b) 210 (c) 2100
  34. 34.Best estimate of 77 × 48? (a) 40000 (b) 400 (c) 4000
  35. 35.Best estimate of 63 × 41? (a) 24000 (b) 240 (c) 2400
  36. 36.Best estimate of 64 × 68? (a) 42000 (b) 420 (c) 4200
  37. 37.Best estimate of 66 × 88? (a) 6300 (b) 630 (c) 63000
  38. 38.Best estimate of 276 + 370? (a) 500 (b) 900 (c) 700
  39. 39.Best estimate of 290 + 731? (a) 1000 (b) 800 (c) 1200
  40. 40.Best estimate of 227 + 192? (a) 400 (b) 200 (c) 600

Answer key

  1. 1800
  2. 3000
  3. 3600
  4. 500
  5. 400
  6. 3500
  7. 6300
  8. 1200
  9. 1400
  10. 600
  11. 1200
  12. 1100
  13. 800
  14. 5000
  15. 1600
  16. 900
  17. 200
  18. 900
  19. 1500
  20. 800
  21. 1000
  22. 1000
  23. 4200
  24. 3000
  25. 600
  26. 1300
  27. 900
  28. 1000
  29. 500
  30. 900
  31. 300
  32. 500
  33. 2100
  34. 4000
  35. 2400
  36. 4200
  37. 6300
  38. 700
  39. 1000
  40. 400

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