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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 221 · 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 40 × 58? (a) 2400 (b) 24000 (c) 240
  2. 2.Best estimate of 226 + 787? (a) 800 (b) 1200 (c) 1000
  3. 3.Best estimate of 53 × 93? (a) 450 (b) 4500 (c) 45000
  4. 4.Best estimate of 769 + 853? (a) 1900 (b) 1500 (c) 1700
  5. 5.Best estimate of 28 × 34? (a) 9000 (b) 900 (c) 90
  6. 6.Best estimate of 191 + 429? (a) 600 (b) 800 (c) 400
  7. 7.Best estimate of 41 × 86? (a) 36000 (b) 360 (c) 3600
  8. 8.Best estimate of 12 × 26? (a) 30 (b) 3000 (c) 300
  9. 9.Best estimate of 77 × 33? (a) 24000 (b) 240 (c) 2400
  10. 10.Best estimate of 213 + 613? (a) 600 (b) 800 (c) 1000
  11. 11.Best estimate of 61 × 68? (a) 4200 (b) 420 (c) 42000
  12. 12.Best estimate of 30 × 96? (a) 3000 (b) 300 (c) 30000
  13. 13.Best estimate of 66 × 40? (a) 2800 (b) 28000 (c) 280
  14. 14.Best estimate of 13 × 48? (a) 500 (b) 5000 (c) 50
  15. 15.Best estimate of 52 × 93? (a) 45000 (b) 4500 (c) 450
  16. 16.Best estimate of 51 × 60? (a) 3000 (b) 300 (c) 30000
  17. 17.Best estimate of 87 × 64? (a) 54000 (b) 5400 (c) 540
  18. 18.Best estimate of 430 + 764? (a) 1000 (b) 1200 (c) 1400
  19. 19.Best estimate of 69 × 18? (a) 140 (b) 1400 (c) 14000
  20. 20.Best estimate of 140 + 448? (a) 700 (b) 300 (c) 500
  21. 21.Best estimate of 556 + 263? (a) 700 (b) 900 (c) 1100
  22. 22.Best estimate of 68 × 42? (a) 28000 (b) 2800 (c) 280
  23. 23.Best estimate of 348 + 233? (a) 300 (b) 500 (c) 700
  24. 24.Best estimate of 60 × 41? (a) 24000 (b) 2400 (c) 240
  25. 25.Best estimate of 219 + 388? (a) 800 (b) 600 (c) 400
  26. 26.Best estimate of 18 × 79? (a) 160 (b) 16000 (c) 1600
  27. 27.Best estimate of 474 + 429? (a) 700 (b) 900 (c) 1100
  28. 28.Best estimate of 67 × 27? (a) 21000 (b) 2100 (c) 210
  29. 29.Best estimate of 36 × 36? (a) 1600 (b) 16000 (c) 160
  30. 30.Best estimate of 14 × 24? (a) 200 (b) 2000 (c) 20
  31. 31.Best estimate of 523 + 681? (a) 1200 (b) 1400 (c) 1000
  32. 32.Best estimate of 67 × 47? (a) 3500 (b) 35000 (c) 350
  33. 33.Best estimate of 787 + 705? (a) 1700 (b) 1300 (c) 1500
  34. 34.Best estimate of 14 × 47? (a) 5000 (b) 50 (c) 500
  35. 35.Best estimate of 519 + 320? (a) 800 (b) 1000 (c) 600
  36. 36.Best estimate of 14 × 78? (a) 80 (b) 800 (c) 8000
  37. 37.Best estimate of 16 × 83? (a) 1600 (b) 16000 (c) 160
  38. 38.Best estimate of 71 × 40? (a) 280 (b) 2800 (c) 28000
  39. 39.Best estimate of 42 × 57? (a) 2400 (b) 240 (c) 24000
  40. 40.Best estimate of 860 + 511? (a) 1200 (b) 1400 (c) 1600

Answer key

  1. 2400
  2. 1000
  3. 4500
  4. 1700
  5. 900
  6. 600
  7. 3600
  8. 300
  9. 2400
  10. 800
  11. 4200
  12. 3000
  13. 2800
  14. 500
  15. 4500
  16. 3000
  17. 5400
  18. 1200
  19. 1400
  20. 500
  21. 900
  22. 2800
  23. 500
  24. 2400
  25. 600
  26. 1600
  27. 900
  28. 2100
  29. 1600
  30. 200
  31. 1200
  32. 3500
  33. 1500
  34. 500
  35. 800
  36. 800
  37. 1600
  38. 2800
  39. 2400
  40. 1400

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