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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 394 · 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 249 + 406? (a) 400 (b) 800 (c) 600
  2. 2.Best estimate of 74 × 32? (a) 2100 (b) 210 (c) 21000
  3. 3.Best estimate of 67 × 96? (a) 70000 (b) 700 (c) 7000
  4. 4.Best estimate of 16 × 88? (a) 18000 (b) 180 (c) 1800
  5. 5.Best estimate of 445 + 409? (a) 1000 (b) 800 (c) 600
  6. 6.Best estimate of 62 × 86? (a) 540 (b) 54000 (c) 5400
  7. 7.Best estimate of 98 × 63? (a) 600 (b) 6000 (c) 60000
  8. 8.Best estimate of 528 + 632? (a) 900 (b) 1100 (c) 1300
  9. 9.Best estimate of 77 × 63? (a) 48000 (b) 4800 (c) 480
  10. 10.Best estimate of 60 × 39? (a) 2400 (b) 240 (c) 24000
  11. 11.Best estimate of 71 × 81? (a) 5600 (b) 56000 (c) 560
  12. 12.Best estimate of 82 × 21? (a) 1600 (b) 160 (c) 16000
  13. 13.Best estimate of 94 × 31? (a) 27000 (b) 2700 (c) 270
  14. 14.Best estimate of 801 + 198? (a) 800 (b) 1000 (c) 1200
  15. 15.Best estimate of 707 + 602? (a) 1100 (b) 1500 (c) 1300
  16. 16.Best estimate of 823 + 222? (a) 1000 (b) 800 (c) 1200
  17. 17.Best estimate of 330 + 262? (a) 600 (b) 800 (c) 400
  18. 18.Best estimate of 299 + 491? (a) 1000 (b) 600 (c) 800
  19. 19.Best estimate of 42 × 54? (a) 20000 (b) 2000 (c) 200
  20. 20.Best estimate of 36 × 72? (a) 280 (b) 2800 (c) 28000
  21. 21.Best estimate of 91 × 44? (a) 360 (b) 3600 (c) 36000
  22. 22.Best estimate of 285 + 761? (a) 1100 (b) 900 (c) 1300
  23. 23.Best estimate of 530 + 301? (a) 600 (b) 1000 (c) 800
  24. 24.Best estimate of 96 × 34? (a) 3000 (b) 30000 (c) 300
  25. 25.Best estimate of 439 + 355? (a) 800 (b) 1000 (c) 600
  26. 26.Best estimate of 87 × 24? (a) 18000 (b) 1800 (c) 180
  27. 27.Best estimate of 29 × 59? (a) 180 (b) 1800 (c) 18000
  28. 28.Best estimate of 87 × 96? (a) 90000 (b) 9000 (c) 900
  29. 29.Best estimate of 67 × 83? (a) 560 (b) 5600 (c) 56000
  30. 30.Best estimate of 363 + 544? (a) 900 (b) 1100 (c) 700
  31. 31.Best estimate of 276 + 284? (a) 400 (b) 600 (c) 800
  32. 32.Best estimate of 32 × 22? (a) 6000 (b) 600 (c) 60
  33. 33.Best estimate of 495 + 213? (a) 900 (b) 700 (c) 500
  34. 34.Best estimate of 166 + 370? (a) 600 (b) 800 (c) 400
  35. 35.Best estimate of 78 × 48? (a) 4000 (b) 400 (c) 40000
  36. 36.Best estimate of 846 + 383? (a) 1200 (b) 1000 (c) 1400
  37. 37.Best estimate of 74 × 26? (a) 2100 (b) 21000 (c) 210
  38. 38.Best estimate of 530 + 608? (a) 1100 (b) 900 (c) 1300
  39. 39.Best estimate of 245 + 663? (a) 900 (b) 700 (c) 1100
  40. 40.Best estimate of 36 × 84? (a) 32000 (b) 3200 (c) 320

Answer key

  1. 600
  2. 2100
  3. 7000
  4. 1800
  5. 800
  6. 5400
  7. 6000
  8. 1100
  9. 4800
  10. 2400
  11. 5600
  12. 1600
  13. 2700
  14. 1000
  15. 1300
  16. 1000
  17. 600
  18. 800
  19. 2000
  20. 2800
  21. 3600
  22. 1100
  23. 800
  24. 3000
  25. 800
  26. 1800
  27. 1800
  28. 9000
  29. 5600
  30. 900
  31. 600
  32. 600
  33. 700
  34. 600
  35. 4000
  36. 1200
  37. 2100
  38. 1100
  39. 900
  40. 3200

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