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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 724 · 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 833 + 854? (a) 1900 (b) 1700 (c) 1500
  2. 2.Best estimate of 19 × 54? (a) 100 (b) 10000 (c) 1000
  3. 3.Best estimate of 135 + 283? (a) 600 (b) 200 (c) 400
  4. 4.Best estimate of 814 + 838? (a) 1800 (b) 1400 (c) 1600
  5. 5.Best estimate of 447 + 172? (a) 400 (b) 800 (c) 600
  6. 6.Best estimate of 305 + 315? (a) 600 (b) 800 (c) 400
  7. 7.Best estimate of 89 × 92? (a) 81000 (b) 810 (c) 8100
  8. 8.Best estimate of 63 × 12? (a) 600 (b) 60 (c) 6000
  9. 9.Best estimate of 772 + 346? (a) 900 (b) 1100 (c) 1300
  10. 10.Best estimate of 485 + 229? (a) 700 (b) 900 (c) 500
  11. 11.Best estimate of 29 × 28? (a) 9000 (b) 90 (c) 900
  12. 12.Best estimate of 27 × 17? (a) 600 (b) 6000 (c) 60
  13. 13.Best estimate of 740 + 283? (a) 1000 (b) 1200 (c) 800
  14. 14.Best estimate of 710 + 630? (a) 1500 (b) 1300 (c) 1100
  15. 15.Best estimate of 854 + 840? (a) 1500 (b) 1700 (c) 1900
  16. 16.Best estimate of 57 × 27? (a) 18000 (b) 1800 (c) 180
  17. 17.Best estimate of 16 × 50? (a) 10000 (b) 1000 (c) 100
  18. 18.Best estimate of 852 + 743? (a) 1400 (b) 1600 (c) 1800
  19. 19.Best estimate of 826 + 737? (a) 1300 (b) 1700 (c) 1500
  20. 20.Best estimate of 262 + 789? (a) 1100 (b) 900 (c) 1300
  21. 21.Best estimate of 284 + 832? (a) 1300 (b) 900 (c) 1100
  22. 22.Best estimate of 61 × 16? (a) 120 (b) 12000 (c) 1200
  23. 23.Best estimate of 52 × 14? (a) 500 (b) 5000 (c) 50
  24. 24.Best estimate of 219 + 554? (a) 600 (b) 1000 (c) 800
  25. 25.Best estimate of 39 × 68? (a) 280 (b) 2800 (c) 28000
  26. 26.Best estimate of 341 + 515? (a) 800 (b) 1000 (c) 600
  27. 27.Best estimate of 17 × 81? (a) 1600 (b) 160 (c) 16000
  28. 28.Best estimate of 98 × 13? (a) 1000 (b) 10000 (c) 100
  29. 29.Best estimate of 337 + 127? (a) 400 (b) 600 (c) 200
  30. 30.Best estimate of 853 + 430? (a) 1100 (b) 1500 (c) 1300
  31. 31.Best estimate of 600 + 338? (a) 1100 (b) 900 (c) 700
  32. 32.Best estimate of 56 × 72? (a) 4200 (b) 420 (c) 42000
  33. 33.Best estimate of 289 + 211? (a) 300 (b) 700 (c) 500
  34. 34.Best estimate of 67 × 14? (a) 7000 (b) 70 (c) 700
  35. 35.Best estimate of 50 × 17? (a) 10000 (b) 1000 (c) 100
  36. 36.Best estimate of 39 × 56? (a) 2400 (b) 24000 (c) 240
  37. 37.Best estimate of 210 + 271? (a) 700 (b) 300 (c) 500
  38. 38.Best estimate of 50 × 12? (a) 50 (b) 5000 (c) 500
  39. 39.Best estimate of 693 + 209? (a) 1100 (b) 900 (c) 700
  40. 40.Best estimate of 204 + 541? (a) 900 (b) 500 (c) 700

Answer key

  1. 1700
  2. 1000
  3. 400
  4. 1600
  5. 600
  6. 600
  7. 8100
  8. 600
  9. 1100
  10. 700
  11. 900
  12. 600
  13. 1000
  14. 1300
  15. 1700
  16. 1800
  17. 1000
  18. 1600
  19. 1500
  20. 1100
  21. 1100
  22. 1200
  23. 500
  24. 800
  25. 2800
  26. 800
  27. 1600
  28. 1000
  29. 400
  30. 1300
  31. 900
  32. 4200
  33. 500
  34. 700
  35. 1000
  36. 2400
  37. 500
  38. 500
  39. 900
  40. 700

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