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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 683 · 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 128 + 193? (a) 300 (b) 100 (c) 500
  2. 2.Best estimate of 23 × 92? (a) 1800 (b) 180 (c) 18000
  3. 3.Best estimate of 76 × 61? (a) 48000 (b) 4800 (c) 480
  4. 4.Best estimate of 56 × 97? (a) 600 (b) 6000 (c) 60000
  5. 5.Best estimate of 165 + 673? (a) 1100 (b) 900 (c) 700
  6. 6.Best estimate of 96 × 12? (a) 1000 (b) 10000 (c) 100
  7. 7.Best estimate of 125 + 560? (a) 700 (b) 500 (c) 900
  8. 8.Best estimate of 249 + 224? (a) 600 (b) 200 (c) 400
  9. 9.Best estimate of 96 × 20? (a) 2000 (b) 20000 (c) 200
  10. 10.Best estimate of 791 + 486? (a) 1300 (b) 1500 (c) 1100
  11. 11.Best estimate of 79 × 83? (a) 64000 (b) 640 (c) 6400
  12. 12.Best estimate of 625 + 198? (a) 1000 (b) 800 (c) 600
  13. 13.Best estimate of 48 × 56? (a) 30000 (b) 300 (c) 3000
  14. 14.Best estimate of 33 × 59? (a) 1800 (b) 18000 (c) 180
  15. 15.Best estimate of 26 × 91? (a) 2700 (b) 270 (c) 27000
  16. 16.Best estimate of 272 + 316? (a) 800 (b) 600 (c) 400
  17. 17.Best estimate of 790 + 160? (a) 1000 (b) 1200 (c) 800
  18. 18.Best estimate of 425 + 587? (a) 1200 (b) 1000 (c) 800
  19. 19.Best estimate of 18 × 89? (a) 1800 (b) 180 (c) 18000
  20. 20.Best estimate of 79 × 78? (a) 6400 (b) 64000 (c) 640
  21. 21.Best estimate of 16 × 20? (a) 4000 (b) 40 (c) 400
  22. 22.Best estimate of 482 + 366? (a) 700 (b) 900 (c) 1100
  23. 23.Best estimate of 37 × 86? (a) 360 (b) 3600 (c) 36000
  24. 24.Best estimate of 56 × 62? (a) 360 (b) 36000 (c) 3600
  25. 25.Best estimate of 716 + 609? (a) 1500 (b) 1100 (c) 1300
  26. 26.Best estimate of 445 + 852? (a) 1500 (b) 1300 (c) 1100
  27. 27.Best estimate of 96 × 13? (a) 1000 (b) 10000 (c) 100
  28. 28.Best estimate of 286 + 555? (a) 900 (b) 1100 (c) 700
  29. 29.Best estimate of 252 + 182? (a) 300 (b) 700 (c) 500
  30. 30.Best estimate of 71 × 19? (a) 14000 (b) 1400 (c) 140
  31. 31.Best estimate of 879 + 841? (a) 1900 (b) 1500 (c) 1700
  32. 32.Best estimate of 844 + 439? (a) 1200 (b) 1400 (c) 1000
  33. 33.Best estimate of 800 + 430? (a) 1200 (b) 1000 (c) 1400
  34. 34.Best estimate of 86 × 71? (a) 6300 (b) 63000 (c) 630
  35. 35.Best estimate of 192 + 152? (a) 600 (b) 400 (c) 200
  36. 36.Best estimate of 58 × 90? (a) 5400 (b) 540 (c) 54000
  37. 37.Best estimate of 34 × 23? (a) 6000 (b) 600 (c) 60
  38. 38.Best estimate of 46 × 51? (a) 25000 (b) 2500 (c) 250
  39. 39.Best estimate of 298 + 225? (a) 300 (b) 700 (c) 500
  40. 40.Best estimate of 79 × 38? (a) 3200 (b) 32000 (c) 320

Answer key

  1. 300
  2. 1800
  3. 4800
  4. 6000
  5. 900
  6. 1000
  7. 700
  8. 400
  9. 2000
  10. 1300
  11. 6400
  12. 800
  13. 3000
  14. 1800
  15. 2700
  16. 600
  17. 1000
  18. 1000
  19. 1800
  20. 6400
  21. 400
  22. 900
  23. 3600
  24. 3600
  25. 1300
  26. 1300
  27. 1000
  28. 900
  29. 500
  30. 1400
  31. 1700
  32. 1200
  33. 1200
  34. 6300
  35. 400
  36. 5400
  37. 600
  38. 2500
  39. 500
  40. 3200

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