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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 358 · 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 528 + 315? (a) 600 (b) 800 (c) 1000
  2. 2.Best estimate of 628 + 465? (a) 1100 (b) 900 (c) 1300
  3. 3.Best estimate of 752 + 130? (a) 900 (b) 1100 (c) 700
  4. 4.Best estimate of 377 + 314? (a) 500 (b) 900 (c) 700
  5. 5.Best estimate of 12 × 21? (a) 20 (b) 200 (c) 2000
  6. 6.Best estimate of 60 × 39? (a) 2400 (b) 24000 (c) 240
  7. 7.Best estimate of 83 × 82? (a) 64000 (b) 640 (c) 6400
  8. 8.Best estimate of 24 × 12? (a) 2000 (b) 20 (c) 200
  9. 9.Best estimate of 41 × 30? (a) 1200 (b) 120 (c) 12000
  10. 10.Best estimate of 873 + 153? (a) 900 (b) 1100 (c) 1300
  11. 11.Best estimate of 88 × 93? (a) 8100 (b) 81000 (c) 810
  12. 12.Best estimate of 61 × 76? (a) 480 (b) 4800 (c) 48000
  13. 13.Best estimate of 12 × 19? (a) 2000 (b) 20 (c) 200
  14. 14.Best estimate of 76 × 28? (a) 240 (b) 24000 (c) 2400
  15. 15.Best estimate of 194 + 661? (a) 1100 (b) 900 (c) 700
  16. 16.Best estimate of 66 × 18? (a) 14000 (b) 1400 (c) 140
  17. 17.Best estimate of 23 × 73? (a) 140 (b) 14000 (c) 1400
  18. 18.Best estimate of 869 + 263? (a) 1400 (b) 1000 (c) 1200
  19. 19.Best estimate of 243 + 875? (a) 1100 (b) 900 (c) 1300
  20. 20.Best estimate of 536 + 695? (a) 1000 (b) 1200 (c) 1400
  21. 21.Best estimate of 73 × 61? (a) 4200 (b) 420 (c) 42000
  22. 22.Best estimate of 867 + 165? (a) 900 (b) 1100 (c) 1300
  23. 23.Best estimate of 320 + 677? (a) 1000 (b) 1200 (c) 800
  24. 24.Best estimate of 152 + 282? (a) 300 (b) 700 (c) 500
  25. 25.Best estimate of 79 × 68? (a) 56000 (b) 5600 (c) 560
  26. 26.Best estimate of 399 + 432? (a) 800 (b) 1000 (c) 600
  27. 27.Best estimate of 80 × 36? (a) 32000 (b) 3200 (c) 320
  28. 28.Best estimate of 81 × 34? (a) 240 (b) 2400 (c) 24000
  29. 29.Best estimate of 16 × 63? (a) 1200 (b) 120 (c) 12000
  30. 30.Best estimate of 51 × 79? (a) 4000 (b) 40000 (c) 400
  31. 31.Best estimate of 226 + 645? (a) 800 (b) 1000 (c) 600
  32. 32.Best estimate of 274 + 879? (a) 1000 (b) 1400 (c) 1200
  33. 33.Best estimate of 186 + 833? (a) 800 (b) 1000 (c) 1200
  34. 34.Best estimate of 66 × 82? (a) 56000 (b) 5600 (c) 560
  35. 35.Best estimate of 552 + 627? (a) 1200 (b) 1000 (c) 1400
  36. 36.Best estimate of 59 × 20? (a) 12000 (b) 120 (c) 1200
  37. 37.Best estimate of 79 × 71? (a) 5600 (b) 56000 (c) 560
  38. 38.Best estimate of 26 × 80? (a) 24000 (b) 2400 (c) 240
  39. 39.Best estimate of 191 + 529? (a) 900 (b) 700 (c) 500
  40. 40.Best estimate of 609 + 484? (a) 1100 (b) 1300 (c) 900

Answer key

  1. 800
  2. 1100
  3. 900
  4. 700
  5. 200
  6. 2400
  7. 6400
  8. 200
  9. 1200
  10. 1100
  11. 8100
  12. 4800
  13. 200
  14. 2400
  15. 900
  16. 1400
  17. 1400
  18. 1200
  19. 1100
  20. 1200
  21. 4200
  22. 1100
  23. 1000
  24. 500
  25. 5600
  26. 800
  27. 3200
  28. 2400
  29. 1200
  30. 4000
  31. 800
  32. 1200
  33. 1000
  34. 5600
  35. 1200
  36. 1200
  37. 5600
  38. 2400
  39. 700
  40. 1100

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