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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 346 · 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 98 × 18? (a) 20000 (b) 2000 (c) 200
  2. 2.Best estimate of 429 + 655? (a) 1100 (b) 1300 (c) 900
  3. 3.Best estimate of 98 × 87? (a) 90000 (b) 900 (c) 9000
  4. 4.Best estimate of 553 + 568? (a) 1400 (b) 1000 (c) 1200
  5. 5.Best estimate of 533 + 147? (a) 800 (b) 400 (c) 600
  6. 6.Best estimate of 66 × 46? (a) 35000 (b) 3500 (c) 350
  7. 7.Best estimate of 413 + 509? (a) 900 (b) 1100 (c) 700
  8. 8.Best estimate of 182 + 415? (a) 800 (b) 400 (c) 600
  9. 9.Best estimate of 42 × 72? (a) 28000 (b) 280 (c) 2800
  10. 10.Best estimate of 155 + 872? (a) 1300 (b) 1100 (c) 900
  11. 11.Best estimate of 68 × 66? (a) 49000 (b) 4900 (c) 490
  12. 12.Best estimate of 64 × 40? (a) 24000 (b) 2400 (c) 240
  13. 13.Best estimate of 77 × 81? (a) 64000 (b) 640 (c) 6400
  14. 14.Best estimate of 229 + 679? (a) 700 (b) 1100 (c) 900
  15. 15.Best estimate of 320 + 174? (a) 500 (b) 700 (c) 300
  16. 16.Best estimate of 843 + 643? (a) 1400 (b) 1600 (c) 1200
  17. 17.Best estimate of 48 × 46? (a) 25000 (b) 250 (c) 2500
  18. 18.Best estimate of 78 × 40? (a) 32000 (b) 320 (c) 3200
  19. 19.Best estimate of 211 + 775? (a) 1000 (b) 800 (c) 1200
  20. 20.Best estimate of 23 × 43? (a) 80 (b) 8000 (c) 800
  21. 21.Best estimate of 442 + 344? (a) 900 (b) 700 (c) 500
  22. 22.Best estimate of 97 × 64? (a) 600 (b) 6000 (c) 60000
  23. 23.Best estimate of 49 × 96? (a) 50000 (b) 500 (c) 5000
  24. 24.Best estimate of 76 × 56? (a) 48000 (b) 4800 (c) 480
  25. 25.Best estimate of 797 + 557? (a) 1400 (b) 1600 (c) 1200
  26. 26.Best estimate of 186 + 424? (a) 800 (b) 600 (c) 400
  27. 27.Best estimate of 338 + 304? (a) 400 (b) 600 (c) 800
  28. 28.Best estimate of 76 × 28? (a) 240 (b) 2400 (c) 24000
  29. 29.Best estimate of 511 + 602? (a) 1300 (b) 1100 (c) 900
  30. 30.Best estimate of 473 + 331? (a) 600 (b) 1000 (c) 800
  31. 31.Best estimate of 254 + 828? (a) 1100 (b) 1300 (c) 900
  32. 32.Best estimate of 259 + 458? (a) 800 (b) 600 (c) 1000
  33. 33.Best estimate of 26 × 96? (a) 300 (b) 3000 (c) 30000
  34. 34.Best estimate of 31 × 14? (a) 3000 (b) 300 (c) 30
  35. 35.Best estimate of 37 × 28? (a) 120 (b) 12000 (c) 1200
  36. 36.Best estimate of 22 × 28? (a) 6000 (b) 60 (c) 600
  37. 37.Best estimate of 566 + 381? (a) 1200 (b) 1000 (c) 800
  38. 38.Best estimate of 377 + 459? (a) 900 (b) 1100 (c) 700
  39. 39.Best estimate of 308 + 207? (a) 700 (b) 500 (c) 300
  40. 40.Best estimate of 825 + 398? (a) 1000 (b) 1400 (c) 1200

Answer key

  1. 2000
  2. 1100
  3. 9000
  4. 1200
  5. 600
  6. 3500
  7. 900
  8. 600
  9. 2800
  10. 1100
  11. 4900
  12. 2400
  13. 6400
  14. 900
  15. 500
  16. 1400
  17. 2500
  18. 3200
  19. 1000
  20. 800
  21. 700
  22. 6000
  23. 5000
  24. 4800
  25. 1400
  26. 600
  27. 600
  28. 2400
  29. 1100
  30. 800
  31. 1100
  32. 800
  33. 3000
  34. 300
  35. 1200
  36. 600
  37. 1000
  38. 900
  39. 500
  40. 1200

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