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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 862 · 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 59 × 66? (a) 42000 (b) 420 (c) 4200
  2. 2.Best estimate of 253 + 192? (a) 300 (b) 500 (c) 700
  3. 3.Best estimate of 33 × 86? (a) 270 (b) 2700 (c) 27000
  4. 4.Best estimate of 741 + 317? (a) 800 (b) 1200 (c) 1000
  5. 5.Best estimate of 33 × 20? (a) 60 (b) 6000 (c) 600
  6. 6.Best estimate of 46 × 56? (a) 30000 (b) 300 (c) 3000
  7. 7.Best estimate of 143 + 329? (a) 400 (b) 600 (c) 200
  8. 8.Best estimate of 92 × 38? (a) 36000 (b) 360 (c) 3600
  9. 9.Best estimate of 37 × 16? (a) 8000 (b) 800 (c) 80
  10. 10.Best estimate of 752 + 815? (a) 1800 (b) 1400 (c) 1600
  11. 11.Best estimate of 803 + 641? (a) 1600 (b) 1200 (c) 1400
  12. 12.Best estimate of 46 × 36? (a) 2000 (b) 20000 (c) 200
  13. 13.Best estimate of 16 × 39? (a) 8000 (b) 80 (c) 800
  14. 14.Best estimate of 49 × 98? (a) 5000 (b) 50000 (c) 500
  15. 15.Best estimate of 89 × 42? (a) 3600 (b) 36000 (c) 360
  16. 16.Best estimate of 66 × 86? (a) 6300 (b) 63000 (c) 630
  17. 17.Best estimate of 416 + 721? (a) 1300 (b) 900 (c) 1100
  18. 18.Best estimate of 40 × 36? (a) 1600 (b) 16000 (c) 160
  19. 19.Best estimate of 59 × 56? (a) 36000 (b) 360 (c) 3600
  20. 20.Best estimate of 23 × 47? (a) 100 (b) 1000 (c) 10000
  21. 21.Best estimate of 412 + 741? (a) 900 (b) 1300 (c) 1100
  22. 22.Best estimate of 96 × 44? (a) 4000 (b) 40000 (c) 400
  23. 23.Best estimate of 12 × 24? (a) 200 (b) 20 (c) 2000
  24. 24.Best estimate of 410 + 301? (a) 900 (b) 500 (c) 700
  25. 25.Best estimate of 454 + 869? (a) 1400 (b) 1600 (c) 1200
  26. 26.Best estimate of 146 + 297? (a) 200 (b) 400 (c) 600
  27. 27.Best estimate of 149 + 431? (a) 700 (b) 300 (c) 500
  28. 28.Best estimate of 285 + 165? (a) 500 (b) 700 (c) 300
  29. 29.Best estimate of 510 + 157? (a) 700 (b) 500 (c) 900
  30. 30.Best estimate of 226 + 734? (a) 1100 (b) 700 (c) 900
  31. 31.Best estimate of 51 × 24? (a) 100 (b) 1000 (c) 10000
  32. 32.Best estimate of 31 × 89? (a) 270 (b) 2700 (c) 27000
  33. 33.Best estimate of 63 × 32? (a) 18000 (b) 180 (c) 1800
  34. 34.Best estimate of 816 + 775? (a) 1800 (b) 1400 (c) 1600
  35. 35.Best estimate of 26 × 20? (a) 600 (b) 6000 (c) 60
  36. 36.Best estimate of 648 + 293? (a) 700 (b) 900 (c) 1100
  37. 37.Best estimate of 56 × 46? (a) 30000 (b) 3000 (c) 300
  38. 38.Best estimate of 251 + 672? (a) 1200 (b) 1000 (c) 800
  39. 39.Best estimate of 79 × 83? (a) 6400 (b) 64000 (c) 640
  40. 40.Best estimate of 74 × 82? (a) 560 (b) 56000 (c) 5600

Answer key

  1. 4200
  2. 500
  3. 2700
  4. 1000
  5. 600
  6. 3000
  7. 400
  8. 3600
  9. 800
  10. 1600
  11. 1400
  12. 2000
  13. 800
  14. 5000
  15. 3600
  16. 6300
  17. 1100
  18. 1600
  19. 3600
  20. 1000
  21. 1100
  22. 4000
  23. 200
  24. 700
  25. 1400
  26. 400
  27. 500
  28. 500
  29. 700
  30. 900
  31. 1000
  32. 2700
  33. 1800
  34. 1600
  35. 600
  36. 900
  37. 3000
  38. 1000
  39. 6400
  40. 5600

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