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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 631 · 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 89 × 69? (a) 6300 (b) 630 (c) 63000
  2. 2.Best estimate of 470 + 677? (a) 1400 (b) 1200 (c) 1000
  3. 3.Best estimate of 260 + 831? (a) 1300 (b) 900 (c) 1100
  4. 4.Best estimate of 97 × 39? (a) 4000 (b) 400 (c) 40000
  5. 5.Best estimate of 200 + 139? (a) 500 (b) 300 (c) 100
  6. 6.Best estimate of 32 × 38? (a) 12000 (b) 120 (c) 1200
  7. 7.Best estimate of 800 + 340? (a) 1100 (b) 1300 (c) 900
  8. 8.Best estimate of 324 + 877? (a) 1200 (b) 1400 (c) 1000
  9. 9.Best estimate of 595 + 320? (a) 900 (b) 1100 (c) 700
  10. 10.Best estimate of 343 + 197? (a) 700 (b) 300 (c) 500
  11. 11.Best estimate of 18 × 76? (a) 1600 (b) 16000 (c) 160
  12. 12.Best estimate of 67 × 81? (a) 56000 (b) 560 (c) 5600
  13. 13.Best estimate of 752 + 197? (a) 1000 (b) 1200 (c) 800
  14. 14.Best estimate of 18 × 41? (a) 80 (b) 800 (c) 8000
  15. 15.Best estimate of 21 × 42? (a) 800 (b) 80 (c) 8000
  16. 16.Best estimate of 74 × 28? (a) 2100 (b) 21000 (c) 210
  17. 17.Best estimate of 97 × 86? (a) 9000 (b) 90000 (c) 900
  18. 18.Best estimate of 64 × 81? (a) 480 (b) 48000 (c) 4800
  19. 19.Best estimate of 32 × 19? (a) 6000 (b) 60 (c) 600
  20. 20.Best estimate of 24 × 94? (a) 18000 (b) 1800 (c) 180
  21. 21.Best estimate of 822 + 563? (a) 1600 (b) 1200 (c) 1400
  22. 22.Best estimate of 197 + 679? (a) 900 (b) 700 (c) 1100
  23. 23.Best estimate of 18 × 92? (a) 1800 (b) 18000 (c) 180
  24. 24.Best estimate of 98 × 77? (a) 80000 (b) 8000 (c) 800
  25. 25.Best estimate of 158 + 432? (a) 400 (b) 800 (c) 600
  26. 26.Best estimate of 33 × 34? (a) 900 (b) 90 (c) 9000
  27. 27.Best estimate of 72 × 33? (a) 2100 (b) 210 (c) 21000
  28. 28.Best estimate of 224 + 757? (a) 800 (b) 1200 (c) 1000
  29. 29.Best estimate of 157 + 660? (a) 700 (b) 900 (c) 1100
  30. 30.Best estimate of 56 × 30? (a) 1800 (b) 180 (c) 18000
  31. 31.Best estimate of 862 + 618? (a) 1500 (b) 1300 (c) 1700
  32. 32.Best estimate of 380 + 180? (a) 400 (b) 800 (c) 600
  33. 33.Best estimate of 69 × 34? (a) 21000 (b) 2100 (c) 210
  34. 34.Best estimate of 84 × 24? (a) 16000 (b) 1600 (c) 160
  35. 35.Best estimate of 32 × 89? (a) 2700 (b) 270 (c) 27000
  36. 36.Best estimate of 58 × 69? (a) 4200 (b) 420 (c) 42000
  37. 37.Best estimate of 66 × 76? (a) 560 (b) 5600 (c) 56000
  38. 38.Best estimate of 40 × 37? (a) 16000 (b) 160 (c) 1600
  39. 39.Best estimate of 24 × 17? (a) 40 (b) 400 (c) 4000
  40. 40.Best estimate of 48 × 24? (a) 10000 (b) 100 (c) 1000

Answer key

  1. 6300
  2. 1200
  3. 1100
  4. 4000
  5. 300
  6. 1200
  7. 1100
  8. 1200
  9. 900
  10. 500
  11. 1600
  12. 5600
  13. 1000
  14. 800
  15. 800
  16. 2100
  17. 9000
  18. 4800
  19. 600
  20. 1800
  21. 1400
  22. 900
  23. 1800
  24. 8000
  25. 600
  26. 900
  27. 2100
  28. 1000
  29. 900
  30. 1800
  31. 1500
  32. 600
  33. 2100
  34. 1600
  35. 2700
  36. 4200
  37. 5600
  38. 1600
  39. 400
  40. 1000

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