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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 565 · 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 547 + 815? (a) 1300 (b) 1500 (c) 1100
  2. 2.Best estimate of 233 + 442? (a) 600 (b) 800 (c) 400
  3. 3.Best estimate of 648 + 428? (a) 800 (b) 1000 (c) 1200
  4. 4.Best estimate of 777 + 402? (a) 1000 (b) 1200 (c) 1400
  5. 5.Best estimate of 556 + 347? (a) 1100 (b) 700 (c) 900
  6. 6.Best estimate of 21 × 30? (a) 600 (b) 60 (c) 6000
  7. 7.Best estimate of 96 × 54? (a) 5000 (b) 50000 (c) 500
  8. 8.Best estimate of 167 + 393? (a) 800 (b) 600 (c) 400
  9. 9.Best estimate of 574 + 457? (a) 1300 (b) 900 (c) 1100
  10. 10.Best estimate of 61 × 23? (a) 120 (b) 1200 (c) 12000
  11. 11.Best estimate of 29 × 33? (a) 90 (b) 900 (c) 9000
  12. 12.Best estimate of 64 × 66? (a) 42000 (b) 4200 (c) 420
  13. 13.Best estimate of 34 × 44? (a) 120 (b) 12000 (c) 1200
  14. 14.Best estimate of 448 + 748? (a) 900 (b) 1100 (c) 1300
  15. 15.Best estimate of 323 + 371? (a) 700 (b) 500 (c) 900
  16. 16.Best estimate of 675 + 621? (a) 1300 (b) 1100 (c) 1500
  17. 17.Best estimate of 812 + 380? (a) 1400 (b) 1000 (c) 1200
  18. 18.Best estimate of 51 × 81? (a) 400 (b) 4000 (c) 40000
  19. 19.Best estimate of 792 + 593? (a) 1600 (b) 1400 (c) 1200
  20. 20.Best estimate of 44 × 30? (a) 1200 (b) 12000 (c) 120
  21. 21.Best estimate of 89 × 52? (a) 4500 (b) 45000 (c) 450
  22. 22.Best estimate of 93 × 12? (a) 90 (b) 9000 (c) 900
  23. 23.Best estimate of 57 × 42? (a) 240 (b) 2400 (c) 24000
  24. 24.Best estimate of 56 × 30? (a) 18000 (b) 1800 (c) 180
  25. 25.Best estimate of 418 + 559? (a) 1000 (b) 1200 (c) 800
  26. 26.Best estimate of 554 + 554? (a) 1400 (b) 1200 (c) 1000
  27. 27.Best estimate of 53 × 46? (a) 25000 (b) 250 (c) 2500
  28. 28.Best estimate of 22 × 72? (a) 14000 (b) 140 (c) 1400
  29. 29.Best estimate of 742 + 420? (a) 900 (b) 1100 (c) 1300
  30. 30.Best estimate of 17 × 21? (a) 4000 (b) 400 (c) 40
  31. 31.Best estimate of 170 + 486? (a) 500 (b) 900 (c) 700
  32. 32.Best estimate of 31 × 52? (a) 15000 (b) 1500 (c) 150
  33. 33.Best estimate of 26 × 83? (a) 2400 (b) 240 (c) 24000
  34. 34.Best estimate of 677 + 252? (a) 1000 (b) 800 (c) 1200
  35. 35.Best estimate of 21 × 13? (a) 2000 (b) 20 (c) 200
  36. 36.Best estimate of 43 × 12? (a) 40 (b) 4000 (c) 400
  37. 37.Best estimate of 90 × 86? (a) 810 (b) 8100 (c) 81000
  38. 38.Best estimate of 617 + 692? (a) 1500 (b) 1300 (c) 1100
  39. 39.Best estimate of 622 + 377? (a) 800 (b) 1000 (c) 1200
  40. 40.Best estimate of 12 × 14? (a) 10 (b) 100 (c) 1000

Answer key

  1. 1300
  2. 600
  3. 1000
  4. 1200
  5. 900
  6. 600
  7. 5000
  8. 600
  9. 1100
  10. 1200
  11. 900
  12. 4200
  13. 1200
  14. 1100
  15. 700
  16. 1300
  17. 1200
  18. 4000
  19. 1400
  20. 1200
  21. 4500
  22. 900
  23. 2400
  24. 1800
  25. 1000
  26. 1200
  27. 2500
  28. 1400
  29. 1100
  30. 400
  31. 700
  32. 1500
  33. 2400
  34. 1000
  35. 200
  36. 400
  37. 8100
  38. 1300
  39. 1000
  40. 100

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