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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 70 · 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 238 + 840? (a) 1200 (b) 1000 (c) 800
  2. 2.Best estimate of 349 + 698? (a) 1200 (b) 800 (c) 1000
  3. 3.Best estimate of 49 × 21? (a) 10000 (b) 1000 (c) 100
  4. 4.Best estimate of 215 + 307? (a) 700 (b) 300 (c) 500
  5. 5.Best estimate of 42 × 23? (a) 8000 (b) 80 (c) 800
  6. 6.Best estimate of 37 × 51? (a) 200 (b) 20000 (c) 2000
  7. 7.Best estimate of 76 × 43? (a) 3200 (b) 32000 (c) 320
  8. 8.Best estimate of 34 × 86? (a) 270 (b) 2700 (c) 27000
  9. 9.Best estimate of 681 + 243? (a) 700 (b) 1100 (c) 900
  10. 10.Best estimate of 308 + 133? (a) 200 (b) 400 (c) 600
  11. 11.Best estimate of 76 × 88? (a) 720 (b) 72000 (c) 7200
  12. 12.Best estimate of 68 × 63? (a) 420 (b) 4200 (c) 42000
  13. 13.Best estimate of 442 + 456? (a) 700 (b) 1100 (c) 900
  14. 14.Best estimate of 87 × 70? (a) 63000 (b) 6300 (c) 630
  15. 15.Best estimate of 69 × 59? (a) 4200 (b) 420 (c) 42000
  16. 16.Best estimate of 48 × 60? (a) 3000 (b) 300 (c) 30000
  17. 17.Best estimate of 485 + 761? (a) 1300 (b) 1100 (c) 1500
  18. 18.Best estimate of 16 × 60? (a) 120 (b) 1200 (c) 12000
  19. 19.Best estimate of 53 × 68? (a) 3500 (b) 350 (c) 35000
  20. 20.Best estimate of 27 × 36? (a) 1200 (b) 12000 (c) 120
  21. 21.Best estimate of 72 × 56? (a) 42000 (b) 4200 (c) 420
  22. 22.Best estimate of 477 + 762? (a) 1100 (b) 1500 (c) 1300
  23. 23.Best estimate of 66 × 26? (a) 2100 (b) 21000 (c) 210
  24. 24.Best estimate of 625 + 795? (a) 1400 (b) 1200 (c) 1600
  25. 25.Best estimate of 16 × 86? (a) 18000 (b) 1800 (c) 180
  26. 26.Best estimate of 477 + 643? (a) 900 (b) 1300 (c) 1100
  27. 27.Best estimate of 143 + 452? (a) 600 (b) 400 (c) 800
  28. 28.Best estimate of 51 × 60? (a) 30000 (b) 300 (c) 3000
  29. 29.Best estimate of 60 × 53? (a) 300 (b) 3000 (c) 30000
  30. 30.Best estimate of 46 × 66? (a) 35000 (b) 350 (c) 3500
  31. 31.Best estimate of 76 × 64? (a) 48000 (b) 480 (c) 4800
  32. 32.Best estimate of 27 × 24? (a) 60 (b) 6000 (c) 600
  33. 33.Best estimate of 225 + 244? (a) 600 (b) 200 (c) 400
  34. 34.Best estimate of 676 + 670? (a) 1200 (b) 1400 (c) 1600
  35. 35.Best estimate of 30 × 67? (a) 2100 (b) 210 (c) 21000
  36. 36.Best estimate of 718 + 336? (a) 1000 (b) 800 (c) 1200
  37. 37.Best estimate of 73 × 34? (a) 210 (b) 21000 (c) 2100
  38. 38.Best estimate of 640 + 363? (a) 1000 (b) 800 (c) 1200
  39. 39.Best estimate of 19 × 53? (a) 1000 (b) 100 (c) 10000
  40. 40.Best estimate of 16 × 27? (a) 600 (b) 60 (c) 6000

Answer key

  1. 1000
  2. 1000
  3. 1000
  4. 500
  5. 800
  6. 2000
  7. 3200
  8. 2700
  9. 900
  10. 400
  11. 7200
  12. 4200
  13. 900
  14. 6300
  15. 4200
  16. 3000
  17. 1300
  18. 1200
  19. 3500
  20. 1200
  21. 4200
  22. 1300
  23. 2100
  24. 1400
  25. 1800
  26. 1100
  27. 600
  28. 3000
  29. 3000
  30. 3500
  31. 4800
  32. 600
  33. 400
  34. 1400
  35. 2100
  36. 1000
  37. 2100
  38. 1000
  39. 1000
  40. 600

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