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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 404 · 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 36 × 78? (a) 320 (b) 32000 (c) 3200
  2. 2.Best estimate of 82 × 66? (a) 56000 (b) 5600 (c) 560
  3. 3.Best estimate of 46 × 41? (a) 20000 (b) 200 (c) 2000
  4. 4.Best estimate of 93 × 98? (a) 900 (b) 90000 (c) 9000
  5. 5.Best estimate of 54 × 39? (a) 2000 (b) 20000 (c) 200
  6. 6.Best estimate of 142 + 611? (a) 900 (b) 500 (c) 700
  7. 7.Best estimate of 689 + 351? (a) 900 (b) 1100 (c) 1300
  8. 8.Best estimate of 53 × 36? (a) 2000 (b) 20000 (c) 200
  9. 9.Best estimate of 32 × 69? (a) 21000 (b) 210 (c) 2100
  10. 10.Best estimate of 37 × 47? (a) 20000 (b) 2000 (c) 200
  11. 11.Best estimate of 422 + 354? (a) 1000 (b) 600 (c) 800
  12. 12.Best estimate of 47 × 51? (a) 2500 (b) 25000 (c) 250
  13. 13.Best estimate of 27 × 26? (a) 9000 (b) 900 (c) 90
  14. 14.Best estimate of 21 × 58? (a) 1200 (b) 12000 (c) 120
  15. 15.Best estimate of 863 + 358? (a) 1500 (b) 1100 (c) 1300
  16. 16.Best estimate of 732 + 730? (a) 1200 (b) 1600 (c) 1400
  17. 17.Best estimate of 330 + 831? (a) 1300 (b) 1100 (c) 900
  18. 18.Best estimate of 696 + 521? (a) 1400 (b) 1200 (c) 1000
  19. 19.Best estimate of 72 × 50? (a) 35000 (b) 3500 (c) 350
  20. 20.Best estimate of 20 × 51? (a) 1000 (b) 100 (c) 10000
  21. 21.Best estimate of 86 × 16? (a) 18000 (b) 1800 (c) 180
  22. 22.Best estimate of 54 × 84? (a) 400 (b) 40000 (c) 4000
  23. 23.Best estimate of 216 + 633? (a) 800 (b) 1000 (c) 600
  24. 24.Best estimate of 698 + 199? (a) 900 (b) 700 (c) 1100
  25. 25.Best estimate of 864 + 603? (a) 1300 (b) 1700 (c) 1500
  26. 26.Best estimate of 54 × 58? (a) 300 (b) 3000 (c) 30000
  27. 27.Best estimate of 383 + 267? (a) 500 (b) 900 (c) 700
  28. 28.Best estimate of 36 × 69? (a) 28000 (b) 2800 (c) 280
  29. 29.Best estimate of 82 × 83? (a) 6400 (b) 64000 (c) 640
  30. 30.Best estimate of 195 + 348? (a) 500 (b) 300 (c) 700
  31. 31.Best estimate of 28 × 86? (a) 2700 (b) 27000 (c) 270
  32. 32.Best estimate of 36 × 41? (a) 160 (b) 1600 (c) 16000
  33. 33.Best estimate of 555 + 275? (a) 1100 (b) 900 (c) 700
  34. 34.Best estimate of 56 × 41? (a) 240 (b) 2400 (c) 24000
  35. 35.Best estimate of 333 + 132? (a) 400 (b) 600 (c) 200
  36. 36.Best estimate of 44 × 66? (a) 2800 (b) 280 (c) 28000
  37. 37.Best estimate of 23 × 26? (a) 60 (b) 600 (c) 6000
  38. 38.Best estimate of 619 + 567? (a) 1400 (b) 1000 (c) 1200
  39. 39.Best estimate of 687 + 662? (a) 1200 (b) 1400 (c) 1600
  40. 40.Best estimate of 640 + 794? (a) 1600 (b) 1400 (c) 1200

Answer key

  1. 3200
  2. 5600
  3. 2000
  4. 9000
  5. 2000
  6. 700
  7. 1100
  8. 2000
  9. 2100
  10. 2000
  11. 800
  12. 2500
  13. 900
  14. 1200
  15. 1300
  16. 1400
  17. 1100
  18. 1200
  19. 3500
  20. 1000
  21. 1800
  22. 4000
  23. 800
  24. 900
  25. 1500
  26. 3000
  27. 700
  28. 2800
  29. 6400
  30. 500
  31. 2700
  32. 1600
  33. 900
  34. 2400
  35. 400
  36. 2800
  37. 600
  38. 1200
  39. 1400
  40. 1400

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