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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 181 · 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 36 × 96? (a) 4000 (b) 40000 (c) 400
  2. 2.Best estimate of 91 × 29? (a) 2700 (b) 270 (c) 27000
  3. 3.Best estimate of 67 × 53? (a) 350 (b) 3500 (c) 35000
  4. 4.Best estimate of 490 + 781? (a) 1500 (b) 1300 (c) 1100
  5. 5.Best estimate of 776 + 477? (a) 1300 (b) 1500 (c) 1100
  6. 6.Best estimate of 471 + 679? (a) 1000 (b) 1400 (c) 1200
  7. 7.Best estimate of 82 × 32? (a) 2400 (b) 24000 (c) 240
  8. 8.Best estimate of 86 × 20? (a) 1800 (b) 180 (c) 18000
  9. 9.Best estimate of 29 × 60? (a) 1800 (b) 18000 (c) 180
  10. 10.Best estimate of 26 × 26? (a) 9000 (b) 90 (c) 900
  11. 11.Best estimate of 88 × 71? (a) 630 (b) 6300 (c) 63000
  12. 12.Best estimate of 24 × 80? (a) 16000 (b) 160 (c) 1600
  13. 13.Best estimate of 364 + 248? (a) 800 (b) 400 (c) 600
  14. 14.Best estimate of 378 + 569? (a) 1000 (b) 800 (c) 1200
  15. 15.Best estimate of 21 × 86? (a) 1800 (b) 18000 (c) 180
  16. 16.Best estimate of 33 × 26? (a) 90 (b) 9000 (c) 900
  17. 17.Best estimate of 74 × 50? (a) 35000 (b) 350 (c) 3500
  18. 18.Best estimate of 326 + 728? (a) 1000 (b) 800 (c) 1200
  19. 19.Best estimate of 419 + 607? (a) 1200 (b) 800 (c) 1000
  20. 20.Best estimate of 669 + 555? (a) 1100 (b) 1500 (c) 1300
  21. 21.Best estimate of 545 + 759? (a) 1500 (b) 1300 (c) 1100
  22. 22.Best estimate of 647 + 845? (a) 1400 (b) 1200 (c) 1600
  23. 23.Best estimate of 74 × 80? (a) 56000 (b) 5600 (c) 560
  24. 24.Best estimate of 83 × 91? (a) 72000 (b) 7200 (c) 720
  25. 25.Best estimate of 89 × 51? (a) 450 (b) 45000 (c) 4500
  26. 26.Best estimate of 90 × 58? (a) 540 (b) 5400 (c) 54000
  27. 27.Best estimate of 26 × 97? (a) 3000 (b) 30000 (c) 300
  28. 28.Best estimate of 211 + 718? (a) 1100 (b) 900 (c) 700
  29. 29.Best estimate of 78 × 89? (a) 7200 (b) 72000 (c) 720
  30. 30.Best estimate of 462 + 722? (a) 1000 (b) 1200 (c) 1400
  31. 31.Best estimate of 86 × 50? (a) 4500 (b) 450 (c) 45000
  32. 32.Best estimate of 540 + 700? (a) 1200 (b) 1400 (c) 1000
  33. 33.Best estimate of 78 × 86? (a) 7200 (b) 720 (c) 72000
  34. 34.Best estimate of 386 + 399? (a) 600 (b) 800 (c) 1000
  35. 35.Best estimate of 741 + 800? (a) 1700 (b) 1300 (c) 1500
  36. 36.Best estimate of 76 × 68? (a) 56000 (b) 560 (c) 5600
  37. 37.Best estimate of 32 × 56? (a) 180 (b) 18000 (c) 1800
  38. 38.Best estimate of 297 + 158? (a) 500 (b) 700 (c) 300
  39. 39.Best estimate of 62 × 60? (a) 360 (b) 36000 (c) 3600
  40. 40.Best estimate of 23 × 87? (a) 1800 (b) 180 (c) 18000

Answer key

  1. 4000
  2. 2700
  3. 3500
  4. 1300
  5. 1300
  6. 1200
  7. 2400
  8. 1800
  9. 1800
  10. 900
  11. 6300
  12. 1600
  13. 600
  14. 1000
  15. 1800
  16. 900
  17. 3500
  18. 1000
  19. 1000
  20. 1300
  21. 1300
  22. 1400
  23. 5600
  24. 7200
  25. 4500
  26. 5400
  27. 3000
  28. 900
  29. 7200
  30. 1200
  31. 4500
  32. 1200
  33. 7200
  34. 800
  35. 1500
  36. 5600
  37. 1800
  38. 500
  39. 3600
  40. 1800

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