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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 240 · 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 96 × 74? (a) 7000 (b) 70000 (c) 700
  2. 2.Best estimate of 497 + 145? (a) 600 (b) 800 (c) 400
  3. 3.Best estimate of 78 × 78? (a) 640 (b) 6400 (c) 64000
  4. 4.Best estimate of 472 + 169? (a) 700 (b) 900 (c) 500
  5. 5.Best estimate of 29 × 53? (a) 1500 (b) 150 (c) 15000
  6. 6.Best estimate of 815 + 714? (a) 1500 (b) 1300 (c) 1700
  7. 7.Best estimate of 36 × 66? (a) 2800 (b) 280 (c) 28000
  8. 8.Best estimate of 251 + 302? (a) 600 (b) 800 (c) 400
  9. 9.Best estimate of 81 × 80? (a) 64000 (b) 640 (c) 6400
  10. 10.Best estimate of 20 × 29? (a) 600 (b) 6000 (c) 60
  11. 11.Best estimate of 47 × 52? (a) 25000 (b) 2500 (c) 250
  12. 12.Best estimate of 567 + 140? (a) 500 (b) 700 (c) 900
  13. 13.Best estimate of 23 × 67? (a) 1400 (b) 14000 (c) 140
  14. 14.Best estimate of 675 + 561? (a) 1300 (b) 1500 (c) 1100
  15. 15.Best estimate of 60 × 52? (a) 3000 (b) 30000 (c) 300
  16. 16.Best estimate of 58 × 28? (a) 18000 (b) 1800 (c) 180
  17. 17.Best estimate of 872 + 416? (a) 1300 (b) 1500 (c) 1100
  18. 18.Best estimate of 822 + 425? (a) 1200 (b) 1000 (c) 1400
  19. 19.Best estimate of 620 + 702? (a) 1300 (b) 1500 (c) 1100
  20. 20.Best estimate of 50 × 41? (a) 2000 (b) 200 (c) 20000
  21. 21.Best estimate of 832 + 651? (a) 1700 (b) 1500 (c) 1300
  22. 22.Best estimate of 68 × 17? (a) 14000 (b) 1400 (c) 140
  23. 23.Best estimate of 153 + 141? (a) 100 (b) 500 (c) 300
  24. 24.Best estimate of 277 + 336? (a) 400 (b) 800 (c) 600
  25. 25.Best estimate of 47 × 26? (a) 150 (b) 15000 (c) 1500
  26. 26.Best estimate of 302 + 129? (a) 200 (b) 600 (c) 400
  27. 27.Best estimate of 86 × 53? (a) 4500 (b) 45000 (c) 450
  28. 28.Best estimate of 505 + 174? (a) 900 (b) 700 (c) 500
  29. 29.Best estimate of 67 × 82? (a) 560 (b) 5600 (c) 56000
  30. 30.Best estimate of 284 + 548? (a) 600 (b) 800 (c) 1000
  31. 31.Best estimate of 54 × 31? (a) 15000 (b) 150 (c) 1500
  32. 32.Best estimate of 52 × 36? (a) 200 (b) 20000 (c) 2000
  33. 33.Best estimate of 22 × 66? (a) 1400 (b) 14000 (c) 140
  34. 34.Best estimate of 514 + 773? (a) 1300 (b) 1500 (c) 1100
  35. 35.Best estimate of 96 × 78? (a) 800 (b) 80000 (c) 8000
  36. 36.Best estimate of 82 × 64? (a) 480 (b) 4800 (c) 48000
  37. 37.Best estimate of 68 × 72? (a) 490 (b) 4900 (c) 49000
  38. 38.Best estimate of 777 + 791? (a) 1800 (b) 1600 (c) 1400
  39. 39.Best estimate of 13 × 14? (a) 10 (b) 100 (c) 1000
  40. 40.Best estimate of 24 × 13? (a) 200 (b) 20 (c) 2000

Answer key

  1. 7000
  2. 600
  3. 6400
  4. 700
  5. 1500
  6. 1500
  7. 2800
  8. 600
  9. 6400
  10. 600
  11. 2500
  12. 700
  13. 1400
  14. 1300
  15. 3000
  16. 1800
  17. 1300
  18. 1200
  19. 1300
  20. 2000
  21. 1500
  22. 1400
  23. 300
  24. 600
  25. 1500
  26. 400
  27. 4500
  28. 700
  29. 5600
  30. 800
  31. 1500
  32. 2000
  33. 1400
  34. 1300
  35. 8000
  36. 4800
  37. 4900
  38. 1600
  39. 100
  40. 200

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