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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 737 · 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 399 + 703? (a) 900 (b) 1300 (c) 1100
  2. 2.Best estimate of 98 × 36? (a) 400 (b) 40000 (c) 4000
  3. 3.Best estimate of 324 + 464? (a) 1000 (b) 600 (c) 800
  4. 4.Best estimate of 664 + 258? (a) 1200 (b) 800 (c) 1000
  5. 5.Best estimate of 61 × 19? (a) 1200 (b) 120 (c) 12000
  6. 6.Best estimate of 56 × 68? (a) 42000 (b) 420 (c) 4200
  7. 7.Best estimate of 31 × 36? (a) 120 (b) 12000 (c) 1200
  8. 8.Best estimate of 741 + 664? (a) 1200 (b) 1600 (c) 1400
  9. 9.Best estimate of 93 × 40? (a) 3600 (b) 36000 (c) 360
  10. 10.Best estimate of 76 × 62? (a) 48000 (b) 480 (c) 4800
  11. 11.Best estimate of 67 × 34? (a) 2100 (b) 210 (c) 21000
  12. 12.Best estimate of 91 × 43? (a) 3600 (b) 360 (c) 36000
  13. 13.Best estimate of 485 + 264? (a) 600 (b) 1000 (c) 800
  14. 14.Best estimate of 96 × 80? (a) 8000 (b) 80000 (c) 800
  15. 15.Best estimate of 177 + 535? (a) 900 (b) 500 (c) 700
  16. 16.Best estimate of 351 + 587? (a) 1200 (b) 1000 (c) 800
  17. 17.Best estimate of 21 × 17? (a) 40 (b) 4000 (c) 400
  18. 18.Best estimate of 91 × 22? (a) 180 (b) 18000 (c) 1800
  19. 19.Best estimate of 26 × 61? (a) 1800 (b) 18000 (c) 180
  20. 20.Best estimate of 239 + 772? (a) 800 (b) 1000 (c) 1200
  21. 21.Best estimate of 535 + 762? (a) 1100 (b) 1300 (c) 1500
  22. 22.Best estimate of 673 + 690? (a) 1600 (b) 1200 (c) 1400
  23. 23.Best estimate of 244 + 665? (a) 900 (b) 1100 (c) 700
  24. 24.Best estimate of 27 × 14? (a) 30 (b) 3000 (c) 300
  25. 25.Best estimate of 93 × 78? (a) 720 (b) 7200 (c) 72000
  26. 26.Best estimate of 499 + 636? (a) 1300 (b) 900 (c) 1100
  27. 27.Best estimate of 86 × 80? (a) 7200 (b) 72000 (c) 720
  28. 28.Best estimate of 38 × 86? (a) 3600 (b) 36000 (c) 360
  29. 29.Best estimate of 16 × 56? (a) 12000 (b) 120 (c) 1200
  30. 30.Best estimate of 33 × 36? (a) 120 (b) 1200 (c) 12000
  31. 31.Best estimate of 354 + 729? (a) 1300 (b) 900 (c) 1100
  32. 32.Best estimate of 43 × 73? (a) 2800 (b) 280 (c) 28000
  33. 33.Best estimate of 74 × 32? (a) 210 (b) 2100 (c) 21000
  34. 34.Best estimate of 243 + 749? (a) 900 (b) 1100 (c) 700
  35. 35.Best estimate of 56 × 16? (a) 1200 (b) 12000 (c) 120
  36. 36.Best estimate of 13 × 13? (a) 1000 (b) 100 (c) 10
  37. 37.Best estimate of 66 × 46? (a) 35000 (b) 3500 (c) 350
  38. 38.Best estimate of 784 + 140? (a) 900 (b) 1100 (c) 700
  39. 39.Best estimate of 90 × 39? (a) 3600 (b) 36000 (c) 360
  40. 40.Best estimate of 130 + 410? (a) 700 (b) 500 (c) 300

Answer key

  1. 1100
  2. 4000
  3. 800
  4. 1000
  5. 1200
  6. 4200
  7. 1200
  8. 1400
  9. 3600
  10. 4800
  11. 2100
  12. 3600
  13. 800
  14. 8000
  15. 700
  16. 1000
  17. 400
  18. 1800
  19. 1800
  20. 1000
  21. 1300
  22. 1400
  23. 900
  24. 300
  25. 7200
  26. 1100
  27. 7200
  28. 3600
  29. 1200
  30. 1200
  31. 1100
  32. 2800
  33. 2100
  34. 900
  35. 1200
  36. 100
  37. 3500
  38. 900
  39. 3600
  40. 500

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