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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 351 · 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 319 + 795? (a) 900 (b) 1300 (c) 1100
  2. 2.Best estimate of 20 × 30? (a) 6000 (b) 600 (c) 60
  3. 3.Best estimate of 61 × 37? (a) 2400 (b) 24000 (c) 240
  4. 4.Best estimate of 720 + 585? (a) 1500 (b) 1300 (c) 1100
  5. 5.Best estimate of 54 × 42? (a) 20000 (b) 200 (c) 2000
  6. 6.Best estimate of 574 + 358? (a) 800 (b) 1200 (c) 1000
  7. 7.Best estimate of 477 + 151? (a) 500 (b) 700 (c) 900
  8. 8.Best estimate of 579 + 643? (a) 1200 (b) 1400 (c) 1000
  9. 9.Best estimate of 41 × 48? (a) 20000 (b) 2000 (c) 200
  10. 10.Best estimate of 39 × 60? (a) 240 (b) 24000 (c) 2400
  11. 11.Best estimate of 299 + 330? (a) 600 (b) 800 (c) 400
  12. 12.Best estimate of 37 × 76? (a) 3200 (b) 320 (c) 32000
  13. 13.Best estimate of 512 + 177? (a) 700 (b) 500 (c) 900
  14. 14.Best estimate of 362 + 689? (a) 1100 (b) 1300 (c) 900
  15. 15.Best estimate of 19 × 64? (a) 120 (b) 12000 (c) 1200
  16. 16.Best estimate of 31 × 22? (a) 60 (b) 6000 (c) 600
  17. 17.Best estimate of 628 + 776? (a) 1200 (b) 1600 (c) 1400
  18. 18.Best estimate of 385 + 866? (a) 1100 (b) 1500 (c) 1300
  19. 19.Best estimate of 77 × 42? (a) 32000 (b) 3200 (c) 320
  20. 20.Best estimate of 76 × 96? (a) 8000 (b) 80000 (c) 800
  21. 21.Best estimate of 92 × 56? (a) 540 (b) 54000 (c) 5400
  22. 22.Best estimate of 12 × 79? (a) 80 (b) 800 (c) 8000
  23. 23.Best estimate of 365 + 154? (a) 600 (b) 800 (c) 400
  24. 24.Best estimate of 399 + 531? (a) 700 (b) 1100 (c) 900
  25. 25.Best estimate of 22 × 13? (a) 20 (b) 200 (c) 2000
  26. 26.Best estimate of 87 × 49? (a) 450 (b) 45000 (c) 4500
  27. 27.Best estimate of 259 + 262? (a) 800 (b) 600 (c) 400
  28. 28.Best estimate of 689 + 351? (a) 1100 (b) 900 (c) 1300
  29. 29.Best estimate of 50 × 77? (a) 4000 (b) 400 (c) 40000
  30. 30.Best estimate of 283 + 219? (a) 300 (b) 700 (c) 500
  31. 31.Best estimate of 475 + 746? (a) 1200 (b) 1000 (c) 1400
  32. 32.Best estimate of 124 + 445? (a) 300 (b) 500 (c) 700
  33. 33.Best estimate of 594 + 294? (a) 700 (b) 900 (c) 1100
  34. 34.Best estimate of 89 × 29? (a) 270 (b) 27000 (c) 2700
  35. 35.Best estimate of 227 + 773? (a) 800 (b) 1200 (c) 1000
  36. 36.Best estimate of 787 + 876? (a) 1900 (b) 1700 (c) 1500
  37. 37.Best estimate of 508 + 486? (a) 1000 (b) 800 (c) 1200
  38. 38.Best estimate of 92 × 26? (a) 27000 (b) 270 (c) 2700
  39. 39.Best estimate of 499 + 124? (a) 800 (b) 400 (c) 600
  40. 40.Best estimate of 423 + 200? (a) 600 (b) 400 (c) 800

Answer key

  1. 1100
  2. 600
  3. 2400
  4. 1300
  5. 2000
  6. 1000
  7. 700
  8. 1200
  9. 2000
  10. 2400
  11. 600
  12. 3200
  13. 700
  14. 1100
  15. 1200
  16. 600
  17. 1400
  18. 1300
  19. 3200
  20. 8000
  21. 5400
  22. 800
  23. 600
  24. 900
  25. 200
  26. 4500
  27. 600
  28. 1100
  29. 4000
  30. 500
  31. 1200
  32. 500
  33. 900
  34. 2700
  35. 1000
  36. 1700
  37. 1000
  38. 2700
  39. 600
  40. 600

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