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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 333 · 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 61 × 90? (a) 54000 (b) 540 (c) 5400
  2. 2.Best estimate of 458 + 287? (a) 800 (b) 600 (c) 1000
  3. 3.Best estimate of 90 × 91? (a) 8100 (b) 81000 (c) 810
  4. 4.Best estimate of 708 + 811? (a) 1700 (b) 1500 (c) 1300
  5. 5.Best estimate of 48 × 88? (a) 4500 (b) 45000 (c) 450
  6. 6.Best estimate of 591 + 837? (a) 1200 (b) 1400 (c) 1600
  7. 7.Best estimate of 615 + 799? (a) 1200 (b) 1600 (c) 1400
  8. 8.Best estimate of 90 × 37? (a) 36000 (b) 3600 (c) 360
  9. 9.Best estimate of 292 + 815? (a) 1300 (b) 900 (c) 1100
  10. 10.Best estimate of 676 + 482? (a) 1400 (b) 1000 (c) 1200
  11. 11.Best estimate of 177 + 293? (a) 500 (b) 700 (c) 300
  12. 12.Best estimate of 83 × 28? (a) 240 (b) 24000 (c) 2400
  13. 13.Best estimate of 22 × 64? (a) 12000 (b) 1200 (c) 120
  14. 14.Best estimate of 81 × 53? (a) 40000 (b) 4000 (c) 400
  15. 15.Best estimate of 515 + 169? (a) 900 (b) 500 (c) 700
  16. 16.Best estimate of 388 + 258? (a) 900 (b) 700 (c) 500
  17. 17.Best estimate of 76 × 82? (a) 64000 (b) 640 (c) 6400
  18. 18.Best estimate of 41 × 12? (a) 400 (b) 4000 (c) 40
  19. 19.Best estimate of 494 + 800? (a) 1100 (b) 1300 (c) 1500
  20. 20.Best estimate of 66 × 39? (a) 28000 (b) 2800 (c) 280
  21. 21.Best estimate of 24 × 78? (a) 16000 (b) 1600 (c) 160
  22. 22.Best estimate of 67 × 73? (a) 490 (b) 4900 (c) 49000
  23. 23.Best estimate of 14 × 90? (a) 90 (b) 900 (c) 9000
  24. 24.Best estimate of 826 + 182? (a) 1200 (b) 800 (c) 1000
  25. 25.Best estimate of 734 + 261? (a) 1000 (b) 1200 (c) 800
  26. 26.Best estimate of 63 × 22? (a) 1200 (b) 12000 (c) 120
  27. 27.Best estimate of 47 × 23? (a) 100 (b) 1000 (c) 10000
  28. 28.Best estimate of 166 + 226? (a) 400 (b) 600 (c) 200
  29. 29.Best estimate of 427 + 870? (a) 1500 (b) 1300 (c) 1100
  30. 30.Best estimate of 76 × 56? (a) 48000 (b) 480 (c) 4800
  31. 31.Best estimate of 590 + 234? (a) 1000 (b) 600 (c) 800
  32. 32.Best estimate of 837 + 466? (a) 1300 (b) 1100 (c) 1500
  33. 33.Best estimate of 49 × 12? (a) 500 (b) 5000 (c) 50
  34. 34.Best estimate of 58 × 56? (a) 3600 (b) 360 (c) 36000
  35. 35.Best estimate of 46 × 28? (a) 150 (b) 1500 (c) 15000
  36. 36.Best estimate of 52 × 92? (a) 4500 (b) 450 (c) 45000
  37. 37.Best estimate of 503 + 660? (a) 1200 (b) 1000 (c) 1400
  38. 38.Best estimate of 19 × 91? (a) 180 (b) 1800 (c) 18000
  39. 39.Best estimate of 41 × 41? (a) 1600 (b) 160 (c) 16000
  40. 40.Best estimate of 72 × 40? (a) 280 (b) 28000 (c) 2800

Answer key

  1. 5400
  2. 800
  3. 8100
  4. 1500
  5. 4500
  6. 1400
  7. 1400
  8. 3600
  9. 1100
  10. 1200
  11. 500
  12. 2400
  13. 1200
  14. 4000
  15. 700
  16. 700
  17. 6400
  18. 400
  19. 1300
  20. 2800
  21. 1600
  22. 4900
  23. 900
  24. 1000
  25. 1000
  26. 1200
  27. 1000
  28. 400
  29. 1300
  30. 4800
  31. 800
  32. 1300
  33. 500
  34. 3600
  35. 1500
  36. 4500
  37. 1200
  38. 1800
  39. 1600
  40. 2800

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