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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 8 · 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 44 × 76? (a) 32000 (b) 320 (c) 3200
  2. 2.Best estimate of 41 × 41? (a) 160 (b) 16000 (c) 1600
  3. 3.Best estimate of 70 × 82? (a) 5600 (b) 56000 (c) 560
  4. 4.Best estimate of 24 × 46? (a) 1000 (b) 100 (c) 10000
  5. 5.Best estimate of 794 + 556? (a) 1200 (b) 1600 (c) 1400
  6. 6.Best estimate of 190 + 322? (a) 300 (b) 700 (c) 500
  7. 7.Best estimate of 76 × 77? (a) 64000 (b) 640 (c) 6400
  8. 8.Best estimate of 36 × 29? (a) 120 (b) 1200 (c) 12000
  9. 9.Best estimate of 248 + 575? (a) 600 (b) 1000 (c) 800
  10. 10.Best estimate of 220 + 632? (a) 1000 (b) 600 (c) 800
  11. 11.Best estimate of 76 × 64? (a) 48000 (b) 480 (c) 4800
  12. 12.Best estimate of 129 + 240? (a) 500 (b) 100 (c) 300
  13. 13.Best estimate of 84 × 44? (a) 320 (b) 32000 (c) 3200
  14. 14.Best estimate of 149 + 604? (a) 500 (b) 700 (c) 900
  15. 15.Best estimate of 77 × 79? (a) 640 (b) 6400 (c) 64000
  16. 16.Best estimate of 635 + 512? (a) 1300 (b) 1100 (c) 900
  17. 17.Best estimate of 123 + 159? (a) 300 (b) 500 (c) 100
  18. 18.Best estimate of 21 × 31? (a) 60 (b) 6000 (c) 600
  19. 19.Best estimate of 346 + 643? (a) 700 (b) 900 (c) 1100
  20. 20.Best estimate of 712 + 314? (a) 800 (b) 1200 (c) 1000
  21. 21.Best estimate of 623 + 314? (a) 700 (b) 1100 (c) 900
  22. 22.Best estimate of 32 × 90? (a) 2700 (b) 27000 (c) 270
  23. 23.Best estimate of 370 + 837? (a) 1400 (b) 1200 (c) 1000
  24. 24.Best estimate of 203 + 287? (a) 500 (b) 700 (c) 300
  25. 25.Best estimate of 28 × 13? (a) 3000 (b) 30 (c) 300
  26. 26.Best estimate of 286 + 839? (a) 1100 (b) 1300 (c) 900
  27. 27.Best estimate of 28 × 30? (a) 9000 (b) 90 (c) 900
  28. 28.Best estimate of 44 × 36? (a) 1600 (b) 16000 (c) 160
  29. 29.Best estimate of 28 × 48? (a) 1500 (b) 150 (c) 15000
  30. 30.Best estimate of 259 + 501? (a) 600 (b) 1000 (c) 800
  31. 31.Best estimate of 48 × 43? (a) 200 (b) 2000 (c) 20000
  32. 32.Best estimate of 32 × 34? (a) 90 (b) 900 (c) 9000
  33. 33.Best estimate of 535 + 456? (a) 1000 (b) 800 (c) 1200
  34. 34.Best estimate of 741 + 877? (a) 1400 (b) 1800 (c) 1600
  35. 35.Best estimate of 36 × 13? (a) 4000 (b) 40 (c) 400
  36. 36.Best estimate of 482 + 593? (a) 900 (b) 1100 (c) 1300
  37. 37.Best estimate of 90 × 68? (a) 630 (b) 63000 (c) 6300
  38. 38.Best estimate of 333 + 163? (a) 300 (b) 700 (c) 500
  39. 39.Best estimate of 856 + 323? (a) 1400 (b) 1200 (c) 1000
  40. 40.Best estimate of 66 × 83? (a) 56000 (b) 5600 (c) 560

Answer key

  1. 3200
  2. 1600
  3. 5600
  4. 1000
  5. 1400
  6. 500
  7. 6400
  8. 1200
  9. 800
  10. 800
  11. 4800
  12. 300
  13. 3200
  14. 700
  15. 6400
  16. 1100
  17. 300
  18. 600
  19. 900
  20. 1000
  21. 900
  22. 2700
  23. 1200
  24. 500
  25. 300
  26. 1100
  27. 900
  28. 1600
  29. 1500
  30. 800
  31. 2000
  32. 900
  33. 1000
  34. 1600
  35. 400
  36. 1100
  37. 6300
  38. 500
  39. 1200
  40. 5600

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