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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 7 · 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 819 + 809? (a) 1600 (b) 1800 (c) 1400
  2. 2.Best estimate of 612 + 213? (a) 1000 (b) 600 (c) 800
  3. 3.Best estimate of 567 + 806? (a) 1600 (b) 1400 (c) 1200
  4. 4.Best estimate of 88 × 93? (a) 810 (b) 8100 (c) 81000
  5. 5.Best estimate of 723 + 530? (a) 1200 (b) 1000 (c) 1400
  6. 6.Best estimate of 19 × 94? (a) 180 (b) 1800 (c) 18000
  7. 7.Best estimate of 235 + 155? (a) 600 (b) 400 (c) 200
  8. 8.Best estimate of 21 × 62? (a) 120 (b) 1200 (c) 12000
  9. 9.Best estimate of 765 + 318? (a) 1300 (b) 900 (c) 1100
  10. 10.Best estimate of 86 × 33? (a) 2700 (b) 270 (c) 27000
  11. 11.Best estimate of 825 + 514? (a) 1500 (b) 1100 (c) 1300
  12. 12.Best estimate of 544 + 647? (a) 900 (b) 1300 (c) 1100
  13. 13.Best estimate of 877 + 861? (a) 1800 (b) 2000 (c) 1600
  14. 14.Best estimate of 92 × 78? (a) 72000 (b) 7200 (c) 720
  15. 15.Best estimate of 37 × 16? (a) 800 (b) 80 (c) 8000
  16. 16.Best estimate of 69 × 42? (a) 280 (b) 2800 (c) 28000
  17. 17.Best estimate of 573 + 317? (a) 700 (b) 1100 (c) 900
  18. 18.Best estimate of 88 × 18? (a) 1800 (b) 18000 (c) 180
  19. 19.Best estimate of 762 + 636? (a) 1200 (b) 1600 (c) 1400
  20. 20.Best estimate of 52 × 78? (a) 40000 (b) 400 (c) 4000
  21. 21.Best estimate of 790 + 139? (a) 1100 (b) 900 (c) 700
  22. 22.Best estimate of 746 + 876? (a) 1400 (b) 1800 (c) 1600
  23. 23.Best estimate of 29 × 20? (a) 60 (b) 600 (c) 6000
  24. 24.Best estimate of 390 + 878? (a) 1300 (b) 1500 (c) 1100
  25. 25.Best estimate of 179 + 333? (a) 700 (b) 300 (c) 500
  26. 26.Best estimate of 448 + 376? (a) 800 (b) 1000 (c) 600
  27. 27.Best estimate of 33 × 60? (a) 1800 (b) 18000 (c) 180
  28. 28.Best estimate of 89 × 13? (a) 90 (b) 900 (c) 9000
  29. 29.Best estimate of 58 × 13? (a) 6000 (b) 600 (c) 60
  30. 30.Best estimate of 423 + 196? (a) 400 (b) 600 (c) 800
  31. 31.Best estimate of 820 + 668? (a) 1700 (b) 1300 (c) 1500
  32. 32.Best estimate of 255 + 598? (a) 1100 (b) 700 (c) 900
  33. 33.Best estimate of 778 + 293? (a) 1100 (b) 1300 (c) 900
  34. 34.Best estimate of 578 + 242? (a) 800 (b) 600 (c) 1000
  35. 35.Best estimate of 82 × 68? (a) 56000 (b) 5600 (c) 560
  36. 36.Best estimate of 37 × 44? (a) 1600 (b) 160 (c) 16000
  37. 37.Best estimate of 194 + 232? (a) 600 (b) 400 (c) 200
  38. 38.Best estimate of 464 + 602? (a) 900 (b) 1300 (c) 1100
  39. 39.Best estimate of 289 + 275? (a) 800 (b) 600 (c) 400
  40. 40.Best estimate of 79 × 91? (a) 72000 (b) 720 (c) 7200

Answer key

  1. 1600
  2. 800
  3. 1400
  4. 8100
  5. 1200
  6. 1800
  7. 400
  8. 1200
  9. 1100
  10. 2700
  11. 1300
  12. 1100
  13. 1800
  14. 7200
  15. 800
  16. 2800
  17. 900
  18. 1800
  19. 1400
  20. 4000
  21. 900
  22. 1600
  23. 600
  24. 1300
  25. 500
  26. 800
  27. 1800
  28. 900
  29. 600
  30. 600
  31. 1500
  32. 900
  33. 1100
  34. 800
  35. 5600
  36. 1600
  37. 400
  38. 1100
  39. 600
  40. 7200

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