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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 460 · 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 53 × 16? (a) 100 (b) 1000 (c) 10000
  2. 2.Best estimate of 509 + 451? (a) 1200 (b) 1000 (c) 800
  3. 3.Best estimate of 361 + 197? (a) 600 (b) 800 (c) 400
  4. 4.Best estimate of 500 + 706? (a) 1000 (b) 1400 (c) 1200
  5. 5.Best estimate of 34 × 72? (a) 210 (b) 21000 (c) 2100
  6. 6.Best estimate of 14 × 28? (a) 3000 (b) 30 (c) 300
  7. 7.Best estimate of 30 × 79? (a) 24000 (b) 240 (c) 2400
  8. 8.Best estimate of 38 × 30? (a) 12000 (b) 120 (c) 1200
  9. 9.Best estimate of 599 + 527? (a) 1300 (b) 900 (c) 1100
  10. 10.Best estimate of 758 + 166? (a) 1000 (b) 800 (c) 1200
  11. 11.Best estimate of 512 + 535? (a) 800 (b) 1200 (c) 1000
  12. 12.Best estimate of 26 × 19? (a) 6000 (b) 60 (c) 600
  13. 13.Best estimate of 246 + 727? (a) 1100 (b) 900 (c) 700
  14. 14.Best estimate of 127 + 651? (a) 600 (b) 1000 (c) 800
  15. 15.Best estimate of 535 + 500? (a) 1000 (b) 800 (c) 1200
  16. 16.Best estimate of 90 × 82? (a) 720 (b) 7200 (c) 72000
  17. 17.Best estimate of 689 + 535? (a) 1200 (b) 1000 (c) 1400
  18. 18.Best estimate of 38 × 44? (a) 1600 (b) 16000 (c) 160
  19. 19.Best estimate of 451 + 778? (a) 1100 (b) 1500 (c) 1300
  20. 20.Best estimate of 757 + 512? (a) 1100 (b) 1300 (c) 1500
  21. 21.Best estimate of 693 + 429? (a) 1300 (b) 1100 (c) 900
  22. 22.Best estimate of 709 + 166? (a) 700 (b) 900 (c) 1100
  23. 23.Best estimate of 46 × 24? (a) 1000 (b) 10000 (c) 100
  24. 24.Best estimate of 16 × 63? (a) 1200 (b) 12000 (c) 120
  25. 25.Best estimate of 31 × 69? (a) 21000 (b) 2100 (c) 210
  26. 26.Best estimate of 186 + 779? (a) 800 (b) 1000 (c) 1200
  27. 27.Best estimate of 24 × 50? (a) 10000 (b) 100 (c) 1000
  28. 28.Best estimate of 27 × 89? (a) 27000 (b) 2700 (c) 270
  29. 29.Best estimate of 61 × 74? (a) 42000 (b) 4200 (c) 420
  30. 30.Best estimate of 160 + 634? (a) 1000 (b) 600 (c) 800
  31. 31.Best estimate of 169 + 725? (a) 1100 (b) 700 (c) 900
  32. 32.Best estimate of 499 + 744? (a) 1200 (b) 1000 (c) 1400
  33. 33.Best estimate of 813 + 623? (a) 1600 (b) 1200 (c) 1400
  34. 34.Best estimate of 33 × 12? (a) 300 (b) 30 (c) 3000
  35. 35.Best estimate of 28 × 19? (a) 6000 (b) 600 (c) 60
  36. 36.Best estimate of 565 + 740? (a) 1300 (b) 1100 (c) 1500
  37. 37.Best estimate of 49 × 24? (a) 10000 (b) 1000 (c) 100
  38. 38.Best estimate of 826 + 368? (a) 1400 (b) 1200 (c) 1000
  39. 39.Best estimate of 284 + 251? (a) 800 (b) 600 (c) 400
  40. 40.Best estimate of 206 + 300? (a) 700 (b) 500 (c) 300

Answer key

  1. 1000
  2. 1000
  3. 600
  4. 1200
  5. 2100
  6. 300
  7. 2400
  8. 1200
  9. 1100
  10. 1000
  11. 1000
  12. 600
  13. 900
  14. 800
  15. 1000
  16. 7200
  17. 1200
  18. 1600
  19. 1300
  20. 1300
  21. 1100
  22. 900
  23. 1000
  24. 1200
  25. 2100
  26. 1000
  27. 1000
  28. 2700
  29. 4200
  30. 800
  31. 900
  32. 1200
  33. 1400
  34. 300
  35. 600
  36. 1300
  37. 1000
  38. 1200
  39. 600
  40. 500

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