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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 429 · 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 249 + 557? (a) 800 (b) 1000 (c) 600
  2. 2.Best estimate of 152 + 866? (a) 1300 (b) 1100 (c) 900
  3. 3.Best estimate of 212 + 231? (a) 600 (b) 200 (c) 400
  4. 4.Best estimate of 32 × 97? (a) 3000 (b) 300 (c) 30000
  5. 5.Best estimate of 545 + 143? (a) 800 (b) 600 (c) 400
  6. 6.Best estimate of 61 × 51? (a) 300 (b) 30000 (c) 3000
  7. 7.Best estimate of 599 + 773? (a) 1600 (b) 1200 (c) 1400
  8. 8.Best estimate of 62 × 26? (a) 1800 (b) 18000 (c) 180
  9. 9.Best estimate of 30 × 90? (a) 27000 (b) 270 (c) 2700
  10. 10.Best estimate of 53 × 41? (a) 20000 (b) 2000 (c) 200
  11. 11.Best estimate of 483 + 865? (a) 1600 (b) 1200 (c) 1400
  12. 12.Best estimate of 14 × 64? (a) 60 (b) 600 (c) 6000
  13. 13.Best estimate of 28 × 80? (a) 240 (b) 24000 (c) 2400
  14. 14.Best estimate of 30 × 26? (a) 9000 (b) 90 (c) 900
  15. 15.Best estimate of 162 + 221? (a) 600 (b) 200 (c) 400
  16. 16.Best estimate of 154 + 328? (a) 500 (b) 700 (c) 300
  17. 17.Best estimate of 321 + 814? (a) 1100 (b) 900 (c) 1300
  18. 18.Best estimate of 26 × 36? (a) 120 (b) 1200 (c) 12000
  19. 19.Best estimate of 24 × 83? (a) 160 (b) 1600 (c) 16000
  20. 20.Best estimate of 539 + 269? (a) 800 (b) 1000 (c) 600
  21. 21.Best estimate of 22 × 29? (a) 600 (b) 6000 (c) 60
  22. 22.Best estimate of 97 × 70? (a) 7000 (b) 70000 (c) 700
  23. 23.Best estimate of 683 + 740? (a) 1400 (b) 1200 (c) 1600
  24. 24.Best estimate of 76 × 66? (a) 5600 (b) 560 (c) 56000
  25. 25.Best estimate of 22 × 34? (a) 60 (b) 6000 (c) 600
  26. 26.Best estimate of 399 + 714? (a) 900 (b) 1300 (c) 1100
  27. 27.Best estimate of 36 × 29? (a) 12000 (b) 1200 (c) 120
  28. 28.Best estimate of 778 + 461? (a) 1500 (b) 1100 (c) 1300
  29. 29.Best estimate of 556 + 356? (a) 1200 (b) 1000 (c) 800
  30. 30.Best estimate of 669 + 567? (a) 1500 (b) 1100 (c) 1300
  31. 31.Best estimate of 327 + 592? (a) 700 (b) 1100 (c) 900
  32. 32.Best estimate of 391 + 506? (a) 700 (b) 1100 (c) 900
  33. 33.Best estimate of 194 + 843? (a) 1000 (b) 1200 (c) 800
  34. 34.Best estimate of 489 + 620? (a) 900 (b) 1300 (c) 1100
  35. 35.Best estimate of 173 + 383? (a) 800 (b) 600 (c) 400
  36. 36.Best estimate of 74 × 20? (a) 14000 (b) 1400 (c) 140
  37. 37.Best estimate of 171 + 177? (a) 200 (b) 400 (c) 600
  38. 38.Best estimate of 71 × 36? (a) 28000 (b) 2800 (c) 280
  39. 39.Best estimate of 16 × 44? (a) 8000 (b) 800 (c) 80
  40. 40.Best estimate of 58 × 98? (a) 600 (b) 6000 (c) 60000

Answer key

  1. 800
  2. 1100
  3. 400
  4. 3000
  5. 600
  6. 3000
  7. 1400
  8. 1800
  9. 2700
  10. 2000
  11. 1400
  12. 600
  13. 2400
  14. 900
  15. 400
  16. 500
  17. 1100
  18. 1200
  19. 1600
  20. 800
  21. 600
  22. 7000
  23. 1400
  24. 5600
  25. 600
  26. 1100
  27. 1200
  28. 1300
  29. 1000
  30. 1300
  31. 900
  32. 900
  33. 1000
  34. 1100
  35. 600
  36. 1400
  37. 400
  38. 2800
  39. 800
  40. 6000

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