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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 824 · 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 553 + 133? (a) 700 (b) 900 (c) 500
  2. 2.Best estimate of 144 + 542? (a) 400 (b) 800 (c) 600
  3. 3.Best estimate of 53 × 26? (a) 1500 (b) 150 (c) 15000
  4. 4.Best estimate of 349 + 728? (a) 1200 (b) 800 (c) 1000
  5. 5.Best estimate of 564 + 616? (a) 1400 (b) 1000 (c) 1200
  6. 6.Best estimate of 89 × 13? (a) 90 (b) 9000 (c) 900
  7. 7.Best estimate of 97 × 16? (a) 200 (b) 20000 (c) 2000
  8. 8.Best estimate of 19 × 76? (a) 16000 (b) 160 (c) 1600
  9. 9.Best estimate of 34 × 19? (a) 6000 (b) 600 (c) 60
  10. 10.Best estimate of 14 × 47? (a) 5000 (b) 50 (c) 500
  11. 11.Best estimate of 73 × 64? (a) 42000 (b) 4200 (c) 420
  12. 12.Best estimate of 76 × 80? (a) 64000 (b) 6400 (c) 640
  13. 13.Best estimate of 351 + 536? (a) 900 (b) 1100 (c) 700
  14. 14.Best estimate of 50 × 18? (a) 10000 (b) 1000 (c) 100
  15. 15.Best estimate of 12 × 33? (a) 3000 (b) 30 (c) 300
  16. 16.Best estimate of 37 × 69? (a) 280 (b) 28000 (c) 2800
  17. 17.Best estimate of 36 × 73? (a) 2800 (b) 28000 (c) 280
  18. 18.Best estimate of 575 + 802? (a) 1600 (b) 1200 (c) 1400
  19. 19.Best estimate of 94 × 87? (a) 8100 (b) 81000 (c) 810
  20. 20.Best estimate of 96 × 92? (a) 90000 (b) 9000 (c) 900
  21. 21.Best estimate of 61 × 80? (a) 4800 (b) 48000 (c) 480
  22. 22.Best estimate of 71 × 71? (a) 4900 (b) 490 (c) 49000
  23. 23.Best estimate of 385 + 615? (a) 1200 (b) 800 (c) 1000
  24. 24.Best estimate of 222 + 615? (a) 600 (b) 800 (c) 1000
  25. 25.Best estimate of 328 + 146? (a) 600 (b) 400 (c) 200
  26. 26.Best estimate of 476 + 558? (a) 1300 (b) 900 (c) 1100
  27. 27.Best estimate of 51 × 46? (a) 25000 (b) 250 (c) 2500
  28. 28.Best estimate of 62 × 81? (a) 4800 (b) 48000 (c) 480
  29. 29.Best estimate of 251 + 204? (a) 300 (b) 500 (c) 700
  30. 30.Best estimate of 770 + 321? (a) 1300 (b) 900 (c) 1100
  31. 31.Best estimate of 270 + 651? (a) 800 (b) 1000 (c) 1200
  32. 32.Best estimate of 72 × 21? (a) 14000 (b) 1400 (c) 140
  33. 33.Best estimate of 277 + 371? (a) 500 (b) 900 (c) 700
  34. 34.Best estimate of 77 × 96? (a) 8000 (b) 800 (c) 80000
  35. 35.Best estimate of 649 + 451? (a) 900 (b) 1300 (c) 1100
  36. 36.Best estimate of 524 + 258? (a) 800 (b) 600 (c) 1000
  37. 37.Best estimate of 618 + 441? (a) 1000 (b) 1200 (c) 800
  38. 38.Best estimate of 56 × 49? (a) 30000 (b) 300 (c) 3000
  39. 39.Best estimate of 297 + 176? (a) 500 (b) 700 (c) 300
  40. 40.Best estimate of 79 × 63? (a) 48000 (b) 4800 (c) 480

Answer key

  1. 700
  2. 600
  3. 1500
  4. 1000
  5. 1200
  6. 900
  7. 2000
  8. 1600
  9. 600
  10. 500
  11. 4200
  12. 6400
  13. 900
  14. 1000
  15. 300
  16. 2800
  17. 2800
  18. 1400
  19. 8100
  20. 9000
  21. 4800
  22. 4900
  23. 1000
  24. 800
  25. 400
  26. 1100
  27. 2500
  28. 4800
  29. 500
  30. 1100
  31. 1000
  32. 1400
  33. 700
  34. 8000
  35. 1100
  36. 800
  37. 1000
  38. 3000
  39. 500
  40. 4800

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