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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 69 · 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 803 + 257? (a) 1300 (b) 900 (c) 1100
  2. 2.Best estimate of 51 × 86? (a) 4500 (b) 450 (c) 45000
  3. 3.Best estimate of 44 × 26? (a) 1200 (b) 12000 (c) 120
  4. 4.Best estimate of 167 + 172? (a) 600 (b) 400 (c) 200
  5. 5.Best estimate of 80 × 33? (a) 2400 (b) 240 (c) 24000
  6. 6.Best estimate of 440 + 289? (a) 700 (b) 500 (c) 900
  7. 7.Best estimate of 34 × 67? (a) 2100 (b) 21000 (c) 210
  8. 8.Best estimate of 21 × 59? (a) 1200 (b) 12000 (c) 120
  9. 9.Best estimate of 455 + 556? (a) 1300 (b) 1100 (c) 900
  10. 10.Best estimate of 308 + 159? (a) 700 (b) 500 (c) 300
  11. 11.Best estimate of 81 × 61? (a) 4800 (b) 48000 (c) 480
  12. 12.Best estimate of 815 + 790? (a) 1800 (b) 1600 (c) 1400
  13. 13.Best estimate of 217 + 235? (a) 600 (b) 200 (c) 400
  14. 14.Best estimate of 60 × 58? (a) 3600 (b) 36000 (c) 360
  15. 15.Best estimate of 263 + 157? (a) 700 (b) 500 (c) 300
  16. 16.Best estimate of 27 × 26? (a) 90 (b) 900 (c) 9000
  17. 17.Best estimate of 28 × 44? (a) 1200 (b) 12000 (c) 120
  18. 18.Best estimate of 459 + 251? (a) 1000 (b) 600 (c) 800
  19. 19.Best estimate of 406 + 336? (a) 700 (b) 900 (c) 500
  20. 20.Best estimate of 67 × 22? (a) 1400 (b) 14000 (c) 140
  21. 21.Best estimate of 791 + 803? (a) 1400 (b) 1800 (c) 1600
  22. 22.Best estimate of 54 × 51? (a) 25000 (b) 2500 (c) 250
  23. 23.Best estimate of 26 × 93? (a) 2700 (b) 27000 (c) 270
  24. 24.Best estimate of 23 × 90? (a) 180 (b) 18000 (c) 1800
  25. 25.Best estimate of 26 × 18? (a) 6000 (b) 600 (c) 60
  26. 26.Best estimate of 89 × 14? (a) 9000 (b) 90 (c) 900
  27. 27.Best estimate of 29 × 82? (a) 24000 (b) 2400 (c) 240
  28. 28.Best estimate of 409 + 169? (a) 400 (b) 600 (c) 800
  29. 29.Best estimate of 16 × 92? (a) 180 (b) 18000 (c) 1800
  30. 30.Best estimate of 33 × 56? (a) 180 (b) 1800 (c) 18000
  31. 31.Best estimate of 49 × 81? (a) 40000 (b) 400 (c) 4000
  32. 32.Best estimate of 522 + 579? (a) 1300 (b) 900 (c) 1100
  33. 33.Best estimate of 97 × 34? (a) 3000 (b) 30000 (c) 300
  34. 34.Best estimate of 245 + 152? (a) 200 (b) 600 (c) 400
  35. 35.Best estimate of 419 + 580? (a) 1000 (b) 1200 (c) 800
  36. 36.Best estimate of 229 + 572? (a) 1000 (b) 800 (c) 600
  37. 37.Best estimate of 83 × 44? (a) 32000 (b) 320 (c) 3200
  38. 38.Best estimate of 60 × 70? (a) 420 (b) 42000 (c) 4200
  39. 39.Best estimate of 58 × 56? (a) 3600 (b) 36000 (c) 360
  40. 40.Best estimate of 96 × 32? (a) 300 (b) 30000 (c) 3000

Answer key

  1. 1100
  2. 4500
  3. 1200
  4. 400
  5. 2400
  6. 700
  7. 2100
  8. 1200
  9. 1100
  10. 500
  11. 4800
  12. 1600
  13. 400
  14. 3600
  15. 500
  16. 900
  17. 1200
  18. 800
  19. 700
  20. 1400
  21. 1600
  22. 2500
  23. 2700
  24. 1800
  25. 600
  26. 900
  27. 2400
  28. 600
  29. 1800
  30. 1800
  31. 4000
  32. 1100
  33. 3000
  34. 400
  35. 1000
  36. 800
  37. 3200
  38. 4200
  39. 3600
  40. 3000

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