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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 107 · 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 722 + 369? (a) 1100 (b) 1300 (c) 900
  2. 2.Best estimate of 30 × 86? (a) 270 (b) 27000 (c) 2700
  3. 3.Best estimate of 284 + 245? (a) 700 (b) 500 (c) 300
  4. 4.Best estimate of 33 × 22? (a) 600 (b) 60 (c) 6000
  5. 5.Best estimate of 46 × 67? (a) 350 (b) 35000 (c) 3500
  6. 6.Best estimate of 40 × 47? (a) 20000 (b) 2000 (c) 200
  7. 7.Best estimate of 30 × 18? (a) 60 (b) 6000 (c) 600
  8. 8.Best estimate of 124 + 266? (a) 200 (b) 600 (c) 400
  9. 9.Best estimate of 21 × 33? (a) 60 (b) 6000 (c) 600
  10. 10.Best estimate of 159 + 177? (a) 200 (b) 400 (c) 600
  11. 11.Best estimate of 70 × 38? (a) 28000 (b) 280 (c) 2800
  12. 12.Best estimate of 31 × 20? (a) 6000 (b) 600 (c) 60
  13. 13.Best estimate of 17 × 86? (a) 1800 (b) 18000 (c) 180
  14. 14.Best estimate of 161 + 763? (a) 800 (b) 1200 (c) 1000
  15. 15.Best estimate of 50 × 68? (a) 35000 (b) 3500 (c) 350
  16. 16.Best estimate of 26 × 81? (a) 240 (b) 2400 (c) 24000
  17. 17.Best estimate of 20 × 31? (a) 600 (b) 6000 (c) 60
  18. 18.Best estimate of 41 × 69? (a) 280 (b) 2800 (c) 28000
  19. 19.Best estimate of 80 × 49? (a) 40000 (b) 4000 (c) 400
  20. 20.Best estimate of 41 × 49? (a) 200 (b) 20000 (c) 2000
  21. 21.Best estimate of 537 + 243? (a) 900 (b) 500 (c) 700
  22. 22.Best estimate of 265 + 364? (a) 500 (b) 700 (c) 900
  23. 23.Best estimate of 66 × 16? (a) 1400 (b) 14000 (c) 140
  24. 24.Best estimate of 63 × 78? (a) 480 (b) 4800 (c) 48000
  25. 25.Best estimate of 619 + 532? (a) 1300 (b) 1100 (c) 900
  26. 26.Best estimate of 97 × 58? (a) 6000 (b) 60000 (c) 600
  27. 27.Best estimate of 721 + 667? (a) 1200 (b) 1600 (c) 1400
  28. 28.Best estimate of 539 + 140? (a) 400 (b) 600 (c) 800
  29. 29.Best estimate of 22 × 58? (a) 120 (b) 12000 (c) 1200
  30. 30.Best estimate of 37 × 76? (a) 3200 (b) 320 (c) 32000
  31. 31.Best estimate of 82 × 37? (a) 3200 (b) 320 (c) 32000
  32. 32.Best estimate of 18 × 87? (a) 1800 (b) 180 (c) 18000
  33. 33.Best estimate of 765 + 528? (a) 1500 (b) 1100 (c) 1300
  34. 34.Best estimate of 713 + 425? (a) 1300 (b) 1100 (c) 900
  35. 35.Best estimate of 26 × 31? (a) 90 (b) 9000 (c) 900
  36. 36.Best estimate of 81 × 62? (a) 480 (b) 48000 (c) 4800
  37. 37.Best estimate of 90 × 60? (a) 540 (b) 54000 (c) 5400
  38. 38.Best estimate of 36 × 69? (a) 28000 (b) 2800 (c) 280
  39. 39.Best estimate of 26 × 16? (a) 600 (b) 60 (c) 6000
  40. 40.Best estimate of 61 × 33? (a) 18000 (b) 1800 (c) 180

Answer key

  1. 1100
  2. 2700
  3. 500
  4. 600
  5. 3500
  6. 2000
  7. 600
  8. 400
  9. 600
  10. 400
  11. 2800
  12. 600
  13. 1800
  14. 1000
  15. 3500
  16. 2400
  17. 600
  18. 2800
  19. 4000
  20. 2000
  21. 700
  22. 700
  23. 1400
  24. 4800
  25. 1100
  26. 6000
  27. 1400
  28. 600
  29. 1200
  30. 3200
  31. 3200
  32. 1800
  33. 1300
  34. 1100
  35. 900
  36. 4800
  37. 5400
  38. 2800
  39. 600
  40. 1800

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