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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 360 · 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 538 + 543? (a) 800 (b) 1200 (c) 1000
  2. 2.Best estimate of 12 × 14? (a) 100 (b) 1000 (c) 10
  3. 3.Best estimate of 82 × 36? (a) 3200 (b) 32000 (c) 320
  4. 4.Best estimate of 791 + 659? (a) 1500 (b) 1300 (c) 1700
  5. 5.Best estimate of 473 + 513? (a) 1200 (b) 800 (c) 1000
  6. 6.Best estimate of 251 + 832? (a) 1300 (b) 900 (c) 1100
  7. 7.Best estimate of 19 × 32? (a) 6000 (b) 600 (c) 60
  8. 8.Best estimate of 502 + 509? (a) 1000 (b) 800 (c) 1200
  9. 9.Best estimate of 41 × 61? (a) 24000 (b) 2400 (c) 240
  10. 10.Best estimate of 718 + 167? (a) 1100 (b) 900 (c) 700
  11. 11.Best estimate of 758 + 546? (a) 1500 (b) 1100 (c) 1300
  12. 12.Best estimate of 735 + 752? (a) 1500 (b) 1300 (c) 1700
  13. 13.Best estimate of 98 × 98? (a) 100000 (b) 10000 (c) 1000
  14. 14.Best estimate of 695 + 459? (a) 1400 (b) 1000 (c) 1200
  15. 15.Best estimate of 66 × 32? (a) 210 (b) 21000 (c) 2100
  16. 16.Best estimate of 678 + 283? (a) 1000 (b) 1200 (c) 800
  17. 17.Best estimate of 43 × 86? (a) 3600 (b) 360 (c) 36000
  18. 18.Best estimate of 96 × 72? (a) 70000 (b) 7000 (c) 700
  19. 19.Best estimate of 44 × 80? (a) 3200 (b) 32000 (c) 320
  20. 20.Best estimate of 122 + 436? (a) 700 (b) 300 (c) 500
  21. 21.Best estimate of 54 × 74? (a) 35000 (b) 350 (c) 3500
  22. 22.Best estimate of 19 × 81? (a) 160 (b) 1600 (c) 16000
  23. 23.Best estimate of 80 × 72? (a) 56000 (b) 560 (c) 5600
  24. 24.Best estimate of 93 × 54? (a) 450 (b) 4500 (c) 45000
  25. 25.Best estimate of 251 + 165? (a) 500 (b) 700 (c) 300
  26. 26.Best estimate of 192 + 637? (a) 600 (b) 800 (c) 1000
  27. 27.Best estimate of 30 × 68? (a) 210 (b) 2100 (c) 21000
  28. 28.Best estimate of 70 × 39? (a) 2800 (b) 28000 (c) 280
  29. 29.Best estimate of 122 + 675? (a) 1000 (b) 800 (c) 600
  30. 30.Best estimate of 19 × 37? (a) 800 (b) 8000 (c) 80
  31. 31.Best estimate of 84 × 18? (a) 1600 (b) 16000 (c) 160
  32. 32.Best estimate of 98 × 79? (a) 8000 (b) 800 (c) 80000
  33. 33.Best estimate of 87 × 37? (a) 3600 (b) 36000 (c) 360
  34. 34.Best estimate of 596 + 728? (a) 1500 (b) 1300 (c) 1100
  35. 35.Best estimate of 74 × 71? (a) 49000 (b) 490 (c) 4900
  36. 36.Best estimate of 177 + 591? (a) 800 (b) 600 (c) 1000
  37. 37.Best estimate of 368 + 235? (a) 400 (b) 600 (c) 800
  38. 38.Best estimate of 365 + 587? (a) 1000 (b) 1200 (c) 800
  39. 39.Best estimate of 27 × 29? (a) 900 (b) 9000 (c) 90
  40. 40.Best estimate of 879 + 834? (a) 1900 (b) 1500 (c) 1700

Answer key

  1. 1000
  2. 100
  3. 3200
  4. 1500
  5. 1000
  6. 1100
  7. 600
  8. 1000
  9. 2400
  10. 900
  11. 1300
  12. 1500
  13. 10000
  14. 1200
  15. 2100
  16. 1000
  17. 3600
  18. 7000
  19. 3200
  20. 500
  21. 3500
  22. 1600
  23. 5600
  24. 4500
  25. 500
  26. 800
  27. 2100
  28. 2800
  29. 800
  30. 800
  31. 1600
  32. 8000
  33. 3600
  34. 1300
  35. 4900
  36. 800
  37. 600
  38. 1000
  39. 900
  40. 1700

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