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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 424 · 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 449 + 747? (a) 1100 (b) 1300 (c) 900
  2. 2.Best estimate of 589 + 294? (a) 900 (b) 700 (c) 1100
  3. 3.Best estimate of 93 × 28? (a) 2700 (b) 27000 (c) 270
  4. 4.Best estimate of 50 × 24? (a) 10000 (b) 100 (c) 1000
  5. 5.Best estimate of 445 + 415? (a) 800 (b) 600 (c) 1000
  6. 6.Best estimate of 34 × 33? (a) 9000 (b) 90 (c) 900
  7. 7.Best estimate of 871 + 443? (a) 1500 (b) 1300 (c) 1100
  8. 8.Best estimate of 50 × 41? (a) 200 (b) 2000 (c) 20000
  9. 9.Best estimate of 554 + 129? (a) 500 (b) 700 (c) 900
  10. 10.Best estimate of 38 × 80? (a) 32000 (b) 3200 (c) 320
  11. 11.Best estimate of 36 × 70? (a) 2800 (b) 280 (c) 28000
  12. 12.Best estimate of 32 × 42? (a) 120 (b) 1200 (c) 12000
  13. 13.Best estimate of 246 + 429? (a) 800 (b) 600 (c) 400
  14. 14.Best estimate of 631 + 727? (a) 1500 (b) 1300 (c) 1100
  15. 15.Best estimate of 199 + 339? (a) 700 (b) 500 (c) 300
  16. 16.Best estimate of 445 + 388? (a) 600 (b) 1000 (c) 800
  17. 17.Best estimate of 98 × 69? (a) 700 (b) 70000 (c) 7000
  18. 18.Best estimate of 270 + 703? (a) 1000 (b) 800 (c) 1200
  19. 19.Best estimate of 656 + 543? (a) 1400 (b) 1200 (c) 1000
  20. 20.Best estimate of 37 × 90? (a) 36000 (b) 3600 (c) 360
  21. 21.Best estimate of 70 × 57? (a) 42000 (b) 420 (c) 4200
  22. 22.Best estimate of 457 + 314? (a) 1000 (b) 600 (c) 800
  23. 23.Best estimate of 92 × 43? (a) 360 (b) 36000 (c) 3600
  24. 24.Best estimate of 18 × 36? (a) 800 (b) 80 (c) 8000
  25. 25.Best estimate of 538 + 471? (a) 1000 (b) 800 (c) 1200
  26. 26.Best estimate of 711 + 440? (a) 1300 (b) 900 (c) 1100
  27. 27.Best estimate of 319 + 404? (a) 700 (b) 900 (c) 500
  28. 28.Best estimate of 608 + 360? (a) 1200 (b) 1000 (c) 800
  29. 29.Best estimate of 133 + 235? (a) 300 (b) 500 (c) 100
  30. 30.Best estimate of 42 × 50? (a) 200 (b) 20000 (c) 2000
  31. 31.Best estimate of 878 + 498? (a) 1600 (b) 1200 (c) 1400
  32. 32.Best estimate of 28 × 48? (a) 1500 (b) 15000 (c) 150
  33. 33.Best estimate of 838 + 474? (a) 1300 (b) 1500 (c) 1100
  34. 34.Best estimate of 156 + 242? (a) 200 (b) 400 (c) 600
  35. 35.Best estimate of 66 × 16? (a) 140 (b) 1400 (c) 14000
  36. 36.Best estimate of 815 + 680? (a) 1500 (b) 1700 (c) 1300
  37. 37.Best estimate of 67 × 56? (a) 420 (b) 4200 (c) 42000
  38. 38.Best estimate of 56 × 50? (a) 300 (b) 3000 (c) 30000
  39. 39.Best estimate of 634 + 176? (a) 800 (b) 1000 (c) 600
  40. 40.Best estimate of 62 × 66? (a) 420 (b) 4200 (c) 42000

Answer key

  1. 1100
  2. 900
  3. 2700
  4. 1000
  5. 800
  6. 900
  7. 1300
  8. 2000
  9. 700
  10. 3200
  11. 2800
  12. 1200
  13. 600
  14. 1300
  15. 500
  16. 800
  17. 7000
  18. 1000
  19. 1200
  20. 3600
  21. 4200
  22. 800
  23. 3600
  24. 800
  25. 1000
  26. 1100
  27. 700
  28. 1000
  29. 300
  30. 2000
  31. 1400
  32. 1500
  33. 1300
  34. 400
  35. 1400
  36. 1500
  37. 4200
  38. 3000
  39. 800
  40. 4200

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