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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 341 · 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 12 × 78? (a) 800 (b) 80 (c) 8000
  2. 2.Best estimate of 68 × 86? (a) 6300 (b) 630 (c) 63000
  3. 3.Best estimate of 527 + 185? (a) 700 (b) 900 (c) 500
  4. 4.Best estimate of 54 × 59? (a) 30000 (b) 300 (c) 3000
  5. 5.Best estimate of 165 + 284? (a) 700 (b) 500 (c) 300
  6. 6.Best estimate of 21 × 57? (a) 12000 (b) 1200 (c) 120
  7. 7.Best estimate of 521 + 202? (a) 900 (b) 500 (c) 700
  8. 8.Best estimate of 501 + 469? (a) 1200 (b) 800 (c) 1000
  9. 9.Best estimate of 46 × 19? (a) 100 (b) 1000 (c) 10000
  10. 10.Best estimate of 50 × 59? (a) 30000 (b) 300 (c) 3000
  11. 11.Best estimate of 29 × 70? (a) 21000 (b) 2100 (c) 210
  12. 12.Best estimate of 857 + 146? (a) 1000 (b) 1200 (c) 800
  13. 13.Best estimate of 66 × 22? (a) 14000 (b) 1400 (c) 140
  14. 14.Best estimate of 66 × 36? (a) 2800 (b) 280 (c) 28000
  15. 15.Best estimate of 437 + 727? (a) 1300 (b) 900 (c) 1100
  16. 16.Best estimate of 728 + 761? (a) 1500 (b) 1700 (c) 1300
  17. 17.Best estimate of 68 × 42? (a) 2800 (b) 280 (c) 28000
  18. 18.Best estimate of 551 + 512? (a) 1300 (b) 900 (c) 1100
  19. 19.Best estimate of 411 + 156? (a) 400 (b) 600 (c) 800
  20. 20.Best estimate of 67 × 16? (a) 1400 (b) 14000 (c) 140
  21. 21.Best estimate of 13 × 26? (a) 300 (b) 3000 (c) 30
  22. 22.Best estimate of 28 × 80? (a) 240 (b) 24000 (c) 2400
  23. 23.Best estimate of 264 + 398? (a) 900 (b) 700 (c) 500
  24. 24.Best estimate of 14 × 44? (a) 400 (b) 4000 (c) 40
  25. 25.Best estimate of 87 × 47? (a) 45000 (b) 450 (c) 4500
  26. 26.Best estimate of 96 × 97? (a) 1000 (b) 100000 (c) 10000
  27. 27.Best estimate of 69 × 62? (a) 4200 (b) 420 (c) 42000
  28. 28.Best estimate of 80 × 28? (a) 2400 (b) 24000 (c) 240
  29. 29.Best estimate of 761 + 809? (a) 1600 (b) 1400 (c) 1800
  30. 30.Best estimate of 243 + 554? (a) 600 (b) 800 (c) 1000
  31. 31.Best estimate of 878 + 552? (a) 1500 (b) 1300 (c) 1700
  32. 32.Best estimate of 26 × 67? (a) 2100 (b) 21000 (c) 210
  33. 33.Best estimate of 260 + 560? (a) 1100 (b) 900 (c) 700
  34. 34.Best estimate of 31 × 26? (a) 900 (b) 90 (c) 9000
  35. 35.Best estimate of 33 × 41? (a) 120 (b) 1200 (c) 12000
  36. 36.Best estimate of 698 + 878? (a) 1800 (b) 1600 (c) 1400
  37. 37.Best estimate of 38 × 21? (a) 80 (b) 8000 (c) 800
  38. 38.Best estimate of 614 + 247? (a) 1000 (b) 600 (c) 800
  39. 39.Best estimate of 16 × 56? (a) 1200 (b) 12000 (c) 120
  40. 40.Best estimate of 60 × 43? (a) 240 (b) 24000 (c) 2400

Answer key

  1. 800
  2. 6300
  3. 700
  4. 3000
  5. 500
  6. 1200
  7. 700
  8. 1000
  9. 1000
  10. 3000
  11. 2100
  12. 1000
  13. 1400
  14. 2800
  15. 1100
  16. 1500
  17. 2800
  18. 1100
  19. 600
  20. 1400
  21. 300
  22. 2400
  23. 700
  24. 400
  25. 4500
  26. 10000
  27. 4200
  28. 2400
  29. 1600
  30. 800
  31. 1500
  32. 2100
  33. 900
  34. 900
  35. 1200
  36. 1600
  37. 800
  38. 800
  39. 1200
  40. 2400

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