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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 50 · 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 26 × 26? (a) 90 (b) 9000 (c) 900
  2. 2.Best estimate of 535 + 709? (a) 1200 (b) 1000 (c) 1400
  3. 3.Best estimate of 181 + 725? (a) 1100 (b) 900 (c) 700
  4. 4.Best estimate of 16 × 17? (a) 40 (b) 400 (c) 4000
  5. 5.Best estimate of 31 × 70? (a) 210 (b) 21000 (c) 2100
  6. 6.Best estimate of 48 × 43? (a) 2000 (b) 200 (c) 20000
  7. 7.Best estimate of 60 × 91? (a) 540 (b) 54000 (c) 5400
  8. 8.Best estimate of 76 × 30? (a) 24000 (b) 2400 (c) 240
  9. 9.Best estimate of 381 + 835? (a) 1200 (b) 1000 (c) 1400
  10. 10.Best estimate of 47 × 19? (a) 1000 (b) 100 (c) 10000
  11. 11.Best estimate of 523 + 354? (a) 900 (b) 1100 (c) 700
  12. 12.Best estimate of 32 × 92? (a) 270 (b) 27000 (c) 2700
  13. 13.Best estimate of 255 + 739? (a) 800 (b) 1200 (c) 1000
  14. 14.Best estimate of 56 × 20? (a) 1200 (b) 12000 (c) 120
  15. 15.Best estimate of 51 × 63? (a) 3000 (b) 30000 (c) 300
  16. 16.Best estimate of 78 × 38? (a) 3200 (b) 320 (c) 32000
  17. 17.Best estimate of 242 + 277? (a) 700 (b) 500 (c) 300
  18. 18.Best estimate of 296 + 286? (a) 600 (b) 400 (c) 800
  19. 19.Best estimate of 563 + 484? (a) 1100 (b) 1300 (c) 900
  20. 20.Best estimate of 569 + 280? (a) 700 (b) 900 (c) 1100
  21. 21.Best estimate of 616 + 770? (a) 1200 (b) 1600 (c) 1400
  22. 22.Best estimate of 396 + 677? (a) 900 (b) 1100 (c) 1300
  23. 23.Best estimate of 748 + 575? (a) 1300 (b) 1100 (c) 1500
  24. 24.Best estimate of 803 + 587? (a) 1400 (b) 1200 (c) 1600
  25. 25.Best estimate of 93 × 41? (a) 360 (b) 3600 (c) 36000
  26. 26.Best estimate of 483 + 377? (a) 1100 (b) 700 (c) 900
  27. 27.Best estimate of 340 + 871? (a) 1200 (b) 1400 (c) 1000
  28. 28.Best estimate of 88 × 32? (a) 270 (b) 2700 (c) 27000
  29. 29.Best estimate of 776 + 425? (a) 1400 (b) 1000 (c) 1200
  30. 30.Best estimate of 53 × 57? (a) 3000 (b) 30000 (c) 300
  31. 31.Best estimate of 30 × 90? (a) 27000 (b) 270 (c) 2700
  32. 32.Best estimate of 165 + 460? (a) 900 (b) 500 (c) 700
  33. 33.Best estimate of 723 + 310? (a) 1200 (b) 800 (c) 1000
  34. 34.Best estimate of 36 × 84? (a) 3200 (b) 320 (c) 32000
  35. 35.Best estimate of 546 + 442? (a) 1100 (b) 900 (c) 700
  36. 36.Best estimate of 83 × 34? (a) 240 (b) 24000 (c) 2400
  37. 37.Best estimate of 74 × 47? (a) 35000 (b) 3500 (c) 350
  38. 38.Best estimate of 18 × 96? (a) 20000 (b) 2000 (c) 200
  39. 39.Best estimate of 81 × 48? (a) 4000 (b) 40000 (c) 400
  40. 40.Best estimate of 33 × 42? (a) 120 (b) 12000 (c) 1200

Answer key

  1. 900
  2. 1200
  3. 900
  4. 400
  5. 2100
  6. 2000
  7. 5400
  8. 2400
  9. 1200
  10. 1000
  11. 900
  12. 2700
  13. 1000
  14. 1200
  15. 3000
  16. 3200
  17. 500
  18. 600
  19. 1100
  20. 900
  21. 1400
  22. 1100
  23. 1300
  24. 1400
  25. 3600
  26. 900
  27. 1200
  28. 2700
  29. 1200
  30. 3000
  31. 2700
  32. 700
  33. 1000
  34. 3200
  35. 900
  36. 2400
  37. 3500
  38. 2000
  39. 4000
  40. 1200

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