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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 162 · 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 296 + 641? (a) 900 (b) 700 (c) 1100
  2. 2.Best estimate of 78 × 22? (a) 16000 (b) 1600 (c) 160
  3. 3.Best estimate of 523 + 867? (a) 1600 (b) 1400 (c) 1200
  4. 4.Best estimate of 71 × 32? (a) 21000 (b) 210 (c) 2100
  5. 5.Best estimate of 325 + 165? (a) 500 (b) 300 (c) 700
  6. 6.Best estimate of 16 × 27? (a) 60 (b) 600 (c) 6000
  7. 7.Best estimate of 213 + 498? (a) 900 (b) 700 (c) 500
  8. 8.Best estimate of 397 + 123? (a) 300 (b) 500 (c) 700
  9. 9.Best estimate of 476 + 246? (a) 500 (b) 900 (c) 700
  10. 10.Best estimate of 13 × 26? (a) 300 (b) 30 (c) 3000
  11. 11.Best estimate of 130 + 165? (a) 100 (b) 300 (c) 500
  12. 12.Best estimate of 22 × 37? (a) 80 (b) 8000 (c) 800
  13. 13.Best estimate of 864 + 296? (a) 1200 (b) 1000 (c) 1400
  14. 14.Best estimate of 309 + 665? (a) 1000 (b) 1200 (c) 800
  15. 15.Best estimate of 177 + 531? (a) 900 (b) 500 (c) 700
  16. 16.Best estimate of 92 × 52? (a) 45000 (b) 4500 (c) 450
  17. 17.Best estimate of 565 + 760? (a) 1200 (b) 1400 (c) 1600
  18. 18.Best estimate of 286 + 271? (a) 400 (b) 800 (c) 600
  19. 19.Best estimate of 26 × 12? (a) 300 (b) 3000 (c) 30
  20. 20.Best estimate of 607 + 441? (a) 1000 (b) 1200 (c) 800
  21. 21.Best estimate of 861 + 565? (a) 1700 (b) 1300 (c) 1500
  22. 22.Best estimate of 564 + 196? (a) 600 (b) 1000 (c) 800
  23. 23.Best estimate of 82 × 66? (a) 5600 (b) 56000 (c) 560
  24. 24.Best estimate of 64 × 93? (a) 54000 (b) 540 (c) 5400
  25. 25.Best estimate of 64 × 76? (a) 4800 (b) 480 (c) 48000
  26. 26.Best estimate of 26 × 89? (a) 27000 (b) 270 (c) 2700
  27. 27.Best estimate of 218 + 377? (a) 600 (b) 800 (c) 400
  28. 28.Best estimate of 308 + 388? (a) 700 (b) 500 (c) 900
  29. 29.Best estimate of 76 × 93? (a) 720 (b) 72000 (c) 7200
  30. 30.Best estimate of 740 + 564? (a) 1100 (b) 1300 (c) 1500
  31. 31.Best estimate of 271 + 304? (a) 600 (b) 400 (c) 800
  32. 32.Best estimate of 18 × 23? (a) 4000 (b) 40 (c) 400
  33. 33.Best estimate of 71 × 43? (a) 280 (b) 28000 (c) 2800
  34. 34.Best estimate of 274 + 654? (a) 1000 (b) 800 (c) 1200
  35. 35.Best estimate of 636 + 459? (a) 1100 (b) 900 (c) 1300
  36. 36.Best estimate of 371 + 559? (a) 800 (b) 1000 (c) 1200
  37. 37.Best estimate of 298 + 835? (a) 1100 (b) 1300 (c) 900
  38. 38.Best estimate of 309 + 643? (a) 1100 (b) 700 (c) 900
  39. 39.Best estimate of 91 × 57? (a) 54000 (b) 5400 (c) 540
  40. 40.Best estimate of 29 × 64? (a) 1800 (b) 180 (c) 18000

Answer key

  1. 900
  2. 1600
  3. 1400
  4. 2100
  5. 500
  6. 600
  7. 700
  8. 500
  9. 700
  10. 300
  11. 300
  12. 800
  13. 1200
  14. 1000
  15. 700
  16. 4500
  17. 1400
  18. 600
  19. 300
  20. 1000
  21. 1500
  22. 800
  23. 5600
  24. 5400
  25. 4800
  26. 2700
  27. 600
  28. 700
  29. 7200
  30. 1300
  31. 600
  32. 400
  33. 2800
  34. 1000
  35. 1100
  36. 1000
  37. 1100
  38. 900
  39. 5400
  40. 1800

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