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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 745 · 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 29 × 42? (a) 1200 (b) 120 (c) 12000
  2. 2.Best estimate of 298 + 610? (a) 700 (b) 1100 (c) 900
  3. 3.Best estimate of 16 × 49? (a) 10000 (b) 1000 (c) 100
  4. 4.Best estimate of 37 × 12? (a) 400 (b) 40 (c) 4000
  5. 5.Best estimate of 22 × 19? (a) 40 (b) 4000 (c) 400
  6. 6.Best estimate of 692 + 215? (a) 900 (b) 700 (c) 1100
  7. 7.Best estimate of 37 × 50? (a) 2000 (b) 20000 (c) 200
  8. 8.Best estimate of 51 × 89? (a) 450 (b) 45000 (c) 4500
  9. 9.Best estimate of 498 + 601? (a) 1100 (b) 1300 (c) 900
  10. 10.Best estimate of 870 + 173? (a) 1100 (b) 900 (c) 1300
  11. 11.Best estimate of 510 + 179? (a) 500 (b) 700 (c) 900
  12. 12.Best estimate of 358 + 265? (a) 700 (b) 500 (c) 900
  13. 13.Best estimate of 640 + 504? (a) 1100 (b) 1300 (c) 900
  14. 14.Best estimate of 617 + 340? (a) 1100 (b) 700 (c) 900
  15. 15.Best estimate of 16 × 42? (a) 80 (b) 800 (c) 8000
  16. 16.Best estimate of 62 × 33? (a) 1800 (b) 180 (c) 18000
  17. 17.Best estimate of 475 + 304? (a) 600 (b) 1000 (c) 800
  18. 18.Best estimate of 461 + 452? (a) 1000 (b) 1200 (c) 800
  19. 19.Best estimate of 53 × 23? (a) 1000 (b) 10000 (c) 100
  20. 20.Best estimate of 584 + 399? (a) 800 (b) 1200 (c) 1000
  21. 21.Best estimate of 57 × 43? (a) 2400 (b) 24000 (c) 240
  22. 22.Best estimate of 299 + 586? (a) 900 (b) 700 (c) 1100
  23. 23.Best estimate of 583 + 591? (a) 1000 (b) 1400 (c) 1200
  24. 24.Best estimate of 23 × 51? (a) 100 (b) 10000 (c) 1000
  25. 25.Best estimate of 764 + 179? (a) 800 (b) 1000 (c) 1200
  26. 26.Best estimate of 407 + 139? (a) 700 (b) 300 (c) 500
  27. 27.Best estimate of 22 × 23? (a) 4000 (b) 400 (c) 40
  28. 28.Best estimate of 30 × 62? (a) 18000 (b) 1800 (c) 180
  29. 29.Best estimate of 32 × 81? (a) 24000 (b) 240 (c) 2400
  30. 30.Best estimate of 31 × 67? (a) 2100 (b) 21000 (c) 210
  31. 31.Best estimate of 47 × 63? (a) 3000 (b) 300 (c) 30000
  32. 32.Best estimate of 638 + 584? (a) 1000 (b) 1400 (c) 1200
  33. 33.Best estimate of 33 × 22? (a) 600 (b) 60 (c) 6000
  34. 34.Best estimate of 26 × 29? (a) 9000 (b) 900 (c) 90
  35. 35.Best estimate of 27 × 70? (a) 210 (b) 21000 (c) 2100
  36. 36.Best estimate of 13 × 37? (a) 400 (b) 4000 (c) 40
  37. 37.Best estimate of 739 + 662? (a) 1600 (b) 1200 (c) 1400
  38. 38.Best estimate of 430 + 341? (a) 700 (b) 900 (c) 500
  39. 39.Best estimate of 439 + 673? (a) 1100 (b) 1300 (c) 900
  40. 40.Best estimate of 18 × 62? (a) 12000 (b) 120 (c) 1200

Answer key

  1. 1200
  2. 900
  3. 1000
  4. 400
  5. 400
  6. 900
  7. 2000
  8. 4500
  9. 1100
  10. 1100
  11. 700
  12. 700
  13. 1100
  14. 900
  15. 800
  16. 1800
  17. 800
  18. 1000
  19. 1000
  20. 1000
  21. 2400
  22. 900
  23. 1200
  24. 1000
  25. 1000
  26. 500
  27. 400
  28. 1800
  29. 2400
  30. 2100
  31. 3000
  32. 1200
  33. 600
  34. 900
  35. 2100
  36. 400
  37. 1400
  38. 700
  39. 1100
  40. 1200

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