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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 305 · 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 292 + 694? (a) 1000 (b) 1200 (c) 800
  2. 2.Best estimate of 217 + 717? (a) 900 (b) 1100 (c) 700
  3. 3.Best estimate of 96 × 77? (a) 8000 (b) 80000 (c) 800
  4. 4.Best estimate of 96 × 40? (a) 4000 (b) 400 (c) 40000
  5. 5.Best estimate of 46 × 49? (a) 25000 (b) 250 (c) 2500
  6. 6.Best estimate of 72 × 40? (a) 280 (b) 2800 (c) 28000
  7. 7.Best estimate of 254 + 668? (a) 800 (b) 1200 (c) 1000
  8. 8.Best estimate of 57 × 18? (a) 120 (b) 12000 (c) 1200
  9. 9.Best estimate of 691 + 188? (a) 900 (b) 1100 (c) 700
  10. 10.Best estimate of 220 + 265? (a) 300 (b) 500 (c) 700
  11. 11.Best estimate of 29 × 38? (a) 1200 (b) 120 (c) 12000
  12. 12.Best estimate of 543 + 596? (a) 1300 (b) 900 (c) 1100
  13. 13.Best estimate of 48 × 13? (a) 500 (b) 5000 (c) 50
  14. 14.Best estimate of 744 + 311? (a) 1000 (b) 1200 (c) 800
  15. 15.Best estimate of 78 × 68? (a) 5600 (b) 56000 (c) 560
  16. 16.Best estimate of 39 × 14? (a) 4000 (b) 40 (c) 400
  17. 17.Best estimate of 247 + 345? (a) 700 (b) 500 (c) 300
  18. 18.Best estimate of 29 × 42? (a) 1200 (b) 12000 (c) 120
  19. 19.Best estimate of 39 × 46? (a) 2000 (b) 20000 (c) 200
  20. 20.Best estimate of 84 × 71? (a) 5600 (b) 560 (c) 56000
  21. 21.Best estimate of 19 × 22? (a) 4000 (b) 400 (c) 40
  22. 22.Best estimate of 44 × 34? (a) 12000 (b) 1200 (c) 120
  23. 23.Best estimate of 782 + 267? (a) 900 (b) 1300 (c) 1100
  24. 24.Best estimate of 192 + 483? (a) 700 (b) 900 (c) 500
  25. 25.Best estimate of 528 + 538? (a) 800 (b) 1000 (c) 1200
  26. 26.Best estimate of 74 × 86? (a) 6300 (b) 63000 (c) 630
  27. 27.Best estimate of 51 × 26? (a) 150 (b) 1500 (c) 15000
  28. 28.Best estimate of 505 + 209? (a) 500 (b) 900 (c) 700
  29. 29.Best estimate of 148 + 683? (a) 800 (b) 1000 (c) 600
  30. 30.Best estimate of 51 × 89? (a) 45000 (b) 4500 (c) 450
  31. 31.Best estimate of 29 × 93? (a) 27000 (b) 2700 (c) 270
  32. 32.Best estimate of 230 + 328? (a) 700 (b) 300 (c) 500
  33. 33.Best estimate of 804 + 671? (a) 1500 (b) 1700 (c) 1300
  34. 34.Best estimate of 878 + 279? (a) 1200 (b) 1400 (c) 1000
  35. 35.Best estimate of 451 + 370? (a) 900 (b) 1100 (c) 700
  36. 36.Best estimate of 217 + 319? (a) 300 (b) 500 (c) 700
  37. 37.Best estimate of 324 + 194? (a) 300 (b) 700 (c) 500
  38. 38.Best estimate of 832 + 857? (a) 1500 (b) 1700 (c) 1900
  39. 39.Best estimate of 32 × 16? (a) 600 (b) 6000 (c) 60
  40. 40.Best estimate of 49 × 24? (a) 10000 (b) 1000 (c) 100

Answer key

  1. 1000
  2. 900
  3. 8000
  4. 4000
  5. 2500
  6. 2800
  7. 1000
  8. 1200
  9. 900
  10. 500
  11. 1200
  12. 1100
  13. 500
  14. 1000
  15. 5600
  16. 400
  17. 500
  18. 1200
  19. 2000
  20. 5600
  21. 400
  22. 1200
  23. 1100
  24. 700
  25. 1000
  26. 6300
  27. 1500
  28. 700
  29. 800
  30. 4500
  31. 2700
  32. 500
  33. 1500
  34. 1200
  35. 900
  36. 500
  37. 500
  38. 1700
  39. 600
  40. 1000

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