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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 43 · 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 70 × 73? (a) 490 (b) 4900 (c) 49000
  2. 2.Best estimate of 44 × 56? (a) 24000 (b) 240 (c) 2400
  3. 3.Best estimate of 475 + 506? (a) 800 (b) 1200 (c) 1000
  4. 4.Best estimate of 72 × 18? (a) 14000 (b) 1400 (c) 140
  5. 5.Best estimate of 13 × 41? (a) 400 (b) 40 (c) 4000
  6. 6.Best estimate of 24 × 66? (a) 140 (b) 14000 (c) 1400
  7. 7.Best estimate of 205 + 407? (a) 600 (b) 800 (c) 400
  8. 8.Best estimate of 296 + 593? (a) 900 (b) 1100 (c) 700
  9. 9.Best estimate of 66 × 89? (a) 6300 (b) 63000 (c) 630
  10. 10.Best estimate of 789 + 147? (a) 700 (b) 900 (c) 1100
  11. 11.Best estimate of 216 + 348? (a) 700 (b) 300 (c) 500
  12. 12.Best estimate of 69 × 44? (a) 28000 (b) 2800 (c) 280
  13. 13.Best estimate of 48 × 19? (a) 100 (b) 1000 (c) 10000
  14. 14.Best estimate of 434 + 217? (a) 600 (b) 400 (c) 800
  15. 15.Best estimate of 219 + 849? (a) 1200 (b) 800 (c) 1000
  16. 16.Best estimate of 300 + 592? (a) 1100 (b) 700 (c) 900
  17. 17.Best estimate of 679 + 363? (a) 1100 (b) 1300 (c) 900
  18. 18.Best estimate of 133 + 455? (a) 400 (b) 600 (c) 800
  19. 19.Best estimate of 67 × 18? (a) 140 (b) 1400 (c) 14000
  20. 20.Best estimate of 373 + 451? (a) 1100 (b) 900 (c) 700
  21. 21.Best estimate of 14 × 42? (a) 4000 (b) 40 (c) 400
  22. 22.Best estimate of 436 + 643? (a) 800 (b) 1200 (c) 1000
  23. 23.Best estimate of 263 + 777? (a) 900 (b) 1100 (c) 1300
  24. 24.Best estimate of 737 + 347? (a) 1200 (b) 1000 (c) 800
  25. 25.Best estimate of 251 + 132? (a) 600 (b) 400 (c) 200
  26. 26.Best estimate of 98 × 90? (a) 9000 (b) 900 (c) 90000
  27. 27.Best estimate of 40 × 54? (a) 2000 (b) 20000 (c) 200
  28. 28.Best estimate of 597 + 455? (a) 900 (b) 1300 (c) 1100
  29. 29.Best estimate of 98 × 53? (a) 50000 (b) 5000 (c) 500
  30. 30.Best estimate of 204 + 789? (a) 1200 (b) 1000 (c) 800
  31. 31.Best estimate of 40 × 63? (a) 24000 (b) 240 (c) 2400
  32. 32.Best estimate of 80 × 91? (a) 7200 (b) 72000 (c) 720
  33. 33.Best estimate of 406 + 610? (a) 800 (b) 1200 (c) 1000
  34. 34.Best estimate of 52 × 18? (a) 10000 (b) 1000 (c) 100
  35. 35.Best estimate of 78 × 34? (a) 2400 (b) 240 (c) 24000
  36. 36.Best estimate of 33 × 86? (a) 2700 (b) 27000 (c) 270
  37. 37.Best estimate of 53 × 87? (a) 4500 (b) 450 (c) 45000
  38. 38.Best estimate of 364 + 429? (a) 600 (b) 1000 (c) 800
  39. 39.Best estimate of 742 + 164? (a) 700 (b) 900 (c) 1100
  40. 40.Best estimate of 26 × 14? (a) 3000 (b) 30 (c) 300

Answer key

  1. 4900
  2. 2400
  3. 1000
  4. 1400
  5. 400
  6. 1400
  7. 600
  8. 900
  9. 6300
  10. 900
  11. 500
  12. 2800
  13. 1000
  14. 600
  15. 1000
  16. 900
  17. 1100
  18. 600
  19. 1400
  20. 900
  21. 400
  22. 1000
  23. 1100
  24. 1000
  25. 400
  26. 9000
  27. 2000
  28. 1100
  29. 5000
  30. 1000
  31. 2400
  32. 7200
  33. 1000
  34. 1000
  35. 2400
  36. 2700
  37. 4500
  38. 800
  39. 900
  40. 300

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