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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 106 · 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 721 + 749? (a) 1600 (b) 1400 (c) 1200
  2. 2.Best estimate of 439 + 713? (a) 1100 (b) 1300 (c) 900
  3. 3.Best estimate of 834 + 194? (a) 1000 (b) 800 (c) 1200
  4. 4.Best estimate of 543 + 723? (a) 1400 (b) 1000 (c) 1200
  5. 5.Best estimate of 239 + 272? (a) 700 (b) 300 (c) 500
  6. 6.Best estimate of 155 + 593? (a) 600 (b) 1000 (c) 800
  7. 7.Best estimate of 273 + 147? (a) 200 (b) 400 (c) 600
  8. 8.Best estimate of 33 × 32? (a) 9000 (b) 90 (c) 900
  9. 9.Best estimate of 37 × 42? (a) 160 (b) 1600 (c) 16000
  10. 10.Best estimate of 50 × 31? (a) 1500 (b) 15000 (c) 150
  11. 11.Best estimate of 151 + 240? (a) 400 (b) 200 (c) 600
  12. 12.Best estimate of 32 × 59? (a) 180 (b) 1800 (c) 18000
  13. 13.Best estimate of 82 × 14? (a) 80 (b) 800 (c) 8000
  14. 14.Best estimate of 49 × 14? (a) 500 (b) 50 (c) 5000
  15. 15.Best estimate of 431 + 338? (a) 700 (b) 900 (c) 500
  16. 16.Best estimate of 132 + 572? (a) 700 (b) 500 (c) 900
  17. 17.Best estimate of 53 × 27? (a) 150 (b) 1500 (c) 15000
  18. 18.Best estimate of 82 × 63? (a) 480 (b) 48000 (c) 4800
  19. 19.Best estimate of 84 × 91? (a) 7200 (b) 72000 (c) 720
  20. 20.Best estimate of 12 × 43? (a) 40 (b) 400 (c) 4000
  21. 21.Best estimate of 614 + 596? (a) 1200 (b) 1400 (c) 1000
  22. 22.Best estimate of 19 × 52? (a) 1000 (b) 10000 (c) 100
  23. 23.Best estimate of 260 + 302? (a) 600 (b) 800 (c) 400
  24. 24.Best estimate of 325 + 618? (a) 1100 (b) 700 (c) 900
  25. 25.Best estimate of 91 × 51? (a) 45000 (b) 4500 (c) 450
  26. 26.Best estimate of 56 × 31? (a) 1800 (b) 18000 (c) 180
  27. 27.Best estimate of 38 × 64? (a) 24000 (b) 240 (c) 2400
  28. 28.Best estimate of 123 + 678? (a) 600 (b) 1000 (c) 800
  29. 29.Best estimate of 14 × 96? (a) 1000 (b) 10000 (c) 100
  30. 30.Best estimate of 738 + 167? (a) 900 (b) 700 (c) 1100
  31. 31.Best estimate of 299 + 497? (a) 600 (b) 800 (c) 1000
  32. 32.Best estimate of 775 + 154? (a) 800 (b) 1000 (c) 1200
  33. 33.Best estimate of 26 × 26? (a) 900 (b) 9000 (c) 90
  34. 34.Best estimate of 451 + 474? (a) 1200 (b) 800 (c) 1000
  35. 35.Best estimate of 568 + 387? (a) 1000 (b) 800 (c) 1200
  36. 36.Best estimate of 37 × 86? (a) 36000 (b) 3600 (c) 360
  37. 37.Best estimate of 692 + 330? (a) 1000 (b) 800 (c) 1200
  38. 38.Best estimate of 26 × 61? (a) 18000 (b) 1800 (c) 180
  39. 39.Best estimate of 42 × 60? (a) 24000 (b) 240 (c) 2400
  40. 40.Best estimate of 43 × 81? (a) 32000 (b) 320 (c) 3200

Answer key

  1. 1400
  2. 1100
  3. 1000
  4. 1200
  5. 500
  6. 800
  7. 400
  8. 900
  9. 1600
  10. 1500
  11. 400
  12. 1800
  13. 800
  14. 500
  15. 700
  16. 700
  17. 1500
  18. 4800
  19. 7200
  20. 400
  21. 1200
  22. 1000
  23. 600
  24. 900
  25. 4500
  26. 1800
  27. 2400
  28. 800
  29. 1000
  30. 900
  31. 800
  32. 1000
  33. 900
  34. 1000
  35. 1000
  36. 3600
  37. 1000
  38. 1800
  39. 2400
  40. 3200

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