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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 781 · 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 34 × 18? (a) 60 (b) 600 (c) 6000
  2. 2.Best estimate of 380 + 295? (a) 700 (b) 900 (c) 500
  3. 3.Best estimate of 22 × 48? (a) 1000 (b) 100 (c) 10000
  4. 4.Best estimate of 493 + 800? (a) 1500 (b) 1300 (c) 1100
  5. 5.Best estimate of 334 + 846? (a) 900 (b) 1300 (c) 1100
  6. 6.Best estimate of 316 + 400? (a) 500 (b) 900 (c) 700
  7. 7.Best estimate of 186 + 803? (a) 1200 (b) 800 (c) 1000
  8. 8.Best estimate of 190 + 412? (a) 600 (b) 400 (c) 800
  9. 9.Best estimate of 289 + 861? (a) 1200 (b) 1000 (c) 1400
  10. 10.Best estimate of 18 × 78? (a) 1600 (b) 16000 (c) 160
  11. 11.Best estimate of 746 + 612? (a) 1100 (b) 1300 (c) 1500
  12. 12.Best estimate of 89 × 24? (a) 180 (b) 1800 (c) 18000
  13. 13.Best estimate of 829 + 420? (a) 1400 (b) 1200 (c) 1000
  14. 14.Best estimate of 24 × 18? (a) 40 (b) 400 (c) 4000
  15. 15.Best estimate of 629 + 812? (a) 1600 (b) 1400 (c) 1200
  16. 16.Best estimate of 83 × 53? (a) 40000 (b) 400 (c) 4000
  17. 17.Best estimate of 210 + 431? (a) 800 (b) 600 (c) 400
  18. 18.Best estimate of 454 + 839? (a) 1300 (b) 1500 (c) 1100
  19. 19.Best estimate of 746 + 675? (a) 1200 (b) 1400 (c) 1600
  20. 20.Best estimate of 94 × 63? (a) 5400 (b) 54000 (c) 540
  21. 21.Best estimate of 188 + 730? (a) 700 (b) 1100 (c) 900
  22. 22.Best estimate of 12 × 41? (a) 40 (b) 400 (c) 4000
  23. 23.Best estimate of 79 × 27? (a) 24000 (b) 240 (c) 2400
  24. 24.Best estimate of 74 × 83? (a) 5600 (b) 56000 (c) 560
  25. 25.Best estimate of 23 × 56? (a) 1200 (b) 12000 (c) 120
  26. 26.Best estimate of 632 + 131? (a) 500 (b) 700 (c) 900
  27. 27.Best estimate of 89 × 83? (a) 7200 (b) 72000 (c) 720
  28. 28.Best estimate of 130 + 331? (a) 400 (b) 600 (c) 200
  29. 29.Best estimate of 340 + 161? (a) 700 (b) 300 (c) 500
  30. 30.Best estimate of 88 × 96? (a) 900 (b) 9000 (c) 90000
  31. 31.Best estimate of 815 + 711? (a) 1500 (b) 1300 (c) 1700
  32. 32.Best estimate of 41 × 46? (a) 20000 (b) 2000 (c) 200
  33. 33.Best estimate of 686 + 129? (a) 600 (b) 800 (c) 1000
  34. 34.Best estimate of 351 + 362? (a) 800 (b) 600 (c) 1000
  35. 35.Best estimate of 12 × 32? (a) 30 (b) 3000 (c) 300
  36. 36.Best estimate of 573 + 390? (a) 800 (b) 1000 (c) 1200
  37. 37.Best estimate of 66 × 92? (a) 630 (b) 6300 (c) 63000
  38. 38.Best estimate of 578 + 616? (a) 1200 (b) 1400 (c) 1000
  39. 39.Best estimate of 80 × 13? (a) 800 (b) 80 (c) 8000
  40. 40.Best estimate of 90 × 56? (a) 5400 (b) 54000 (c) 540

Answer key

  1. 600
  2. 700
  3. 1000
  4. 1300
  5. 1100
  6. 700
  7. 1000
  8. 600
  9. 1200
  10. 1600
  11. 1300
  12. 1800
  13. 1200
  14. 400
  15. 1400
  16. 4000
  17. 600
  18. 1300
  19. 1400
  20. 5400
  21. 900
  22. 400
  23. 2400
  24. 5600
  25. 1200
  26. 700
  27. 7200
  28. 400
  29. 500
  30. 9000
  31. 1500
  32. 2000
  33. 800
  34. 800
  35. 300
  36. 1000
  37. 6300
  38. 1200
  39. 800
  40. 5400

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