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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 563 · 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 89 × 91? (a) 8100 (b) 81000 (c) 810
  2. 2.Best estimate of 838 + 318? (a) 1100 (b) 900 (c) 1300
  3. 3.Best estimate of 526 + 592? (a) 1300 (b) 900 (c) 1100
  4. 4.Best estimate of 752 + 136? (a) 900 (b) 700 (c) 1100
  5. 5.Best estimate of 37 × 90? (a) 360 (b) 3600 (c) 36000
  6. 6.Best estimate of 713 + 575? (a) 1500 (b) 1100 (c) 1300
  7. 7.Best estimate of 36 × 12? (a) 40 (b) 400 (c) 4000
  8. 8.Best estimate of 26 × 41? (a) 120 (b) 12000 (c) 1200
  9. 9.Best estimate of 503 + 287? (a) 1000 (b) 800 (c) 600
  10. 10.Best estimate of 66 × 92? (a) 63000 (b) 6300 (c) 630
  11. 11.Best estimate of 269 + 401? (a) 700 (b) 900 (c) 500
  12. 12.Best estimate of 69 × 57? (a) 4200 (b) 42000 (c) 420
  13. 13.Best estimate of 599 + 278? (a) 1100 (b) 900 (c) 700
  14. 14.Best estimate of 83 × 94? (a) 72000 (b) 7200 (c) 720
  15. 15.Best estimate of 22 × 62? (a) 120 (b) 12000 (c) 1200
  16. 16.Best estimate of 499 + 879? (a) 1200 (b) 1600 (c) 1400
  17. 17.Best estimate of 78 × 20? (a) 1600 (b) 16000 (c) 160
  18. 18.Best estimate of 211 + 788? (a) 1000 (b) 800 (c) 1200
  19. 19.Best estimate of 379 + 424? (a) 600 (b) 800 (c) 1000
  20. 20.Best estimate of 76 × 58? (a) 4800 (b) 48000 (c) 480
  21. 21.Best estimate of 94 × 66? (a) 630 (b) 63000 (c) 6300
  22. 22.Best estimate of 51 × 13? (a) 5000 (b) 500 (c) 50
  23. 23.Best estimate of 224 + 229? (a) 200 (b) 600 (c) 400
  24. 24.Best estimate of 31 × 64? (a) 18000 (b) 1800 (c) 180
  25. 25.Best estimate of 42 × 30? (a) 12000 (b) 120 (c) 1200
  26. 26.Best estimate of 73 × 71? (a) 490 (b) 49000 (c) 4900
  27. 27.Best estimate of 258 + 420? (a) 700 (b) 900 (c) 500
  28. 28.Best estimate of 703 + 127? (a) 600 (b) 800 (c) 1000
  29. 29.Best estimate of 752 + 694? (a) 1500 (b) 1700 (c) 1300
  30. 30.Best estimate of 31 × 90? (a) 270 (b) 27000 (c) 2700
  31. 31.Best estimate of 76 × 42? (a) 3200 (b) 32000 (c) 320
  32. 32.Best estimate of 384 + 194? (a) 600 (b) 400 (c) 800
  33. 33.Best estimate of 800 + 456? (a) 1300 (b) 1500 (c) 1100
  34. 34.Best estimate of 90 × 96? (a) 900 (b) 9000 (c) 90000
  35. 35.Best estimate of 312 + 687? (a) 1200 (b) 800 (c) 1000
  36. 36.Best estimate of 571 + 734? (a) 1300 (b) 1500 (c) 1100
  37. 37.Best estimate of 42 × 87? (a) 36000 (b) 360 (c) 3600
  38. 38.Best estimate of 30 × 98? (a) 30000 (b) 300 (c) 3000
  39. 39.Best estimate of 374 + 515? (a) 700 (b) 900 (c) 1100
  40. 40.Best estimate of 52 × 71? (a) 3500 (b) 35000 (c) 350

Answer key

  1. 8100
  2. 1100
  3. 1100
  4. 900
  5. 3600
  6. 1300
  7. 400
  8. 1200
  9. 800
  10. 6300
  11. 700
  12. 4200
  13. 900
  14. 7200
  15. 1200
  16. 1400
  17. 1600
  18. 1000
  19. 800
  20. 4800
  21. 6300
  22. 500
  23. 400
  24. 1800
  25. 1200
  26. 4900
  27. 700
  28. 800
  29. 1500
  30. 2700
  31. 3200
  32. 600
  33. 1300
  34. 9000
  35. 1000
  36. 1300
  37. 3600
  38. 3000
  39. 900
  40. 3500

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