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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 618 · 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 210 + 697? (a) 700 (b) 1100 (c) 900
  2. 2.Best estimate of 160 + 859? (a) 1100 (b) 1300 (c) 900
  3. 3.Best estimate of 64 × 63? (a) 360 (b) 36000 (c) 3600
  4. 4.Best estimate of 743 + 816? (a) 1700 (b) 1300 (c) 1500
  5. 5.Best estimate of 50 × 87? (a) 4500 (b) 45000 (c) 450
  6. 6.Best estimate of 84 × 42? (a) 320 (b) 32000 (c) 3200
  7. 7.Best estimate of 92 × 46? (a) 450 (b) 45000 (c) 4500
  8. 8.Best estimate of 67 × 66? (a) 49000 (b) 4900 (c) 490
  9. 9.Best estimate of 46 × 16? (a) 10000 (b) 100 (c) 1000
  10. 10.Best estimate of 496 + 704? (a) 1200 (b) 1000 (c) 1400
  11. 11.Best estimate of 807 + 777? (a) 1600 (b) 1400 (c) 1800
  12. 12.Best estimate of 18 × 58? (a) 120 (b) 12000 (c) 1200
  13. 13.Best estimate of 391 + 468? (a) 1100 (b) 700 (c) 900
  14. 14.Best estimate of 41 × 76? (a) 3200 (b) 32000 (c) 320
  15. 15.Best estimate of 19 × 32? (a) 6000 (b) 600 (c) 60
  16. 16.Best estimate of 30 × 66? (a) 2100 (b) 21000 (c) 210
  17. 17.Best estimate of 61 × 81? (a) 48000 (b) 4800 (c) 480
  18. 18.Best estimate of 373 + 480? (a) 900 (b) 1100 (c) 700
  19. 19.Best estimate of 735 + 813? (a) 1500 (b) 1700 (c) 1300
  20. 20.Best estimate of 126 + 490? (a) 800 (b) 600 (c) 400
  21. 21.Best estimate of 19 × 26? (a) 600 (b) 6000 (c) 60
  22. 22.Best estimate of 42 × 41? (a) 160 (b) 16000 (c) 1600
  23. 23.Best estimate of 87 × 97? (a) 900 (b) 9000 (c) 90000
  24. 24.Best estimate of 50 × 59? (a) 30000 (b) 3000 (c) 300
  25. 25.Best estimate of 86 × 51? (a) 4500 (b) 45000 (c) 450
  26. 26.Best estimate of 24 × 83? (a) 1600 (b) 16000 (c) 160
  27. 27.Best estimate of 46 × 72? (a) 350 (b) 3500 (c) 35000
  28. 28.Best estimate of 27 × 36? (a) 1200 (b) 12000 (c) 120
  29. 29.Best estimate of 26 × 16? (a) 600 (b) 6000 (c) 60
  30. 30.Best estimate of 344 + 183? (a) 700 (b) 500 (c) 300
  31. 31.Best estimate of 96 × 16? (a) 20000 (b) 200 (c) 2000
  32. 32.Best estimate of 78 × 53? (a) 400 (b) 40000 (c) 4000
  33. 33.Best estimate of 37 × 20? (a) 800 (b) 8000 (c) 80
  34. 34.Best estimate of 367 + 788? (a) 1200 (b) 1000 (c) 1400
  35. 35.Best estimate of 51 × 23? (a) 10000 (b) 1000 (c) 100
  36. 36.Best estimate of 64 × 56? (a) 3600 (b) 360 (c) 36000
  37. 37.Best estimate of 26 × 42? (a) 1200 (b) 12000 (c) 120
  38. 38.Best estimate of 752 + 791? (a) 1400 (b) 1800 (c) 1600
  39. 39.Best estimate of 818 + 694? (a) 1700 (b) 1300 (c) 1500
  40. 40.Best estimate of 485 + 817? (a) 1500 (b) 1300 (c) 1100

Answer key

  1. 900
  2. 1100
  3. 3600
  4. 1500
  5. 4500
  6. 3200
  7. 4500
  8. 4900
  9. 1000
  10. 1200
  11. 1600
  12. 1200
  13. 900
  14. 3200
  15. 600
  16. 2100
  17. 4800
  18. 900
  19. 1500
  20. 600
  21. 600
  22. 1600
  23. 9000
  24. 3000
  25. 4500
  26. 1600
  27. 3500
  28. 1200
  29. 600
  30. 500
  31. 2000
  32. 4000
  33. 800
  34. 1200
  35. 1000
  36. 3600
  37. 1200
  38. 1600
  39. 1500
  40. 1300

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