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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 495 · 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 724 + 764? (a) 1700 (b) 1300 (c) 1500
  2. 2.Best estimate of 790 + 737? (a) 1300 (b) 1700 (c) 1500
  3. 3.Best estimate of 21 × 18? (a) 4000 (b) 400 (c) 40
  4. 4.Best estimate of 354 + 576? (a) 1200 (b) 800 (c) 1000
  5. 5.Best estimate of 322 + 132? (a) 600 (b) 200 (c) 400
  6. 6.Best estimate of 31 × 88? (a) 27000 (b) 270 (c) 2700
  7. 7.Best estimate of 49 × 37? (a) 200 (b) 2000 (c) 20000
  8. 8.Best estimate of 66 × 53? (a) 35000 (b) 3500 (c) 350
  9. 9.Best estimate of 273 + 606? (a) 1100 (b) 700 (c) 900
  10. 10.Best estimate of 389 + 736? (a) 900 (b) 1100 (c) 1300
  11. 11.Best estimate of 583 + 324? (a) 900 (b) 1100 (c) 700
  12. 12.Best estimate of 16 × 86? (a) 18000 (b) 1800 (c) 180
  13. 13.Best estimate of 786 + 122? (a) 1100 (b) 900 (c) 700
  14. 14.Best estimate of 798 + 410? (a) 1000 (b) 1200 (c) 1400
  15. 15.Best estimate of 90 × 53? (a) 45000 (b) 450 (c) 4500
  16. 16.Best estimate of 852 + 458? (a) 1400 (b) 1200 (c) 1600
  17. 17.Best estimate of 448 + 535? (a) 700 (b) 900 (c) 1100
  18. 18.Best estimate of 52 × 59? (a) 3000 (b) 300 (c) 30000
  19. 19.Best estimate of 56 × 47? (a) 30000 (b) 300 (c) 3000
  20. 20.Best estimate of 283 + 702? (a) 1000 (b) 800 (c) 1200
  21. 21.Best estimate of 774 + 399? (a) 1400 (b) 1200 (c) 1000
  22. 22.Best estimate of 880 + 126? (a) 1200 (b) 1000 (c) 800
  23. 23.Best estimate of 66 × 12? (a) 700 (b) 7000 (c) 70
  24. 24.Best estimate of 87 × 29? (a) 2700 (b) 27000 (c) 270
  25. 25.Best estimate of 26 × 57? (a) 180 (b) 1800 (c) 18000
  26. 26.Best estimate of 580 + 417? (a) 800 (b) 1200 (c) 1000
  27. 27.Best estimate of 720 + 371? (a) 900 (b) 1300 (c) 1100
  28. 28.Best estimate of 703 + 264? (a) 1000 (b) 800 (c) 1200
  29. 29.Best estimate of 91 × 81? (a) 720 (b) 72000 (c) 7200
  30. 30.Best estimate of 563 + 506? (a) 900 (b) 1300 (c) 1100
  31. 31.Best estimate of 96 × 96? (a) 100000 (b) 10000 (c) 1000
  32. 32.Best estimate of 259 + 618? (a) 1100 (b) 900 (c) 700
  33. 33.Best estimate of 384 + 164? (a) 800 (b) 400 (c) 600
  34. 34.Best estimate of 21 × 12? (a) 2000 (b) 200 (c) 20
  35. 35.Best estimate of 33 × 46? (a) 15000 (b) 150 (c) 1500
  36. 36.Best estimate of 176 + 519? (a) 700 (b) 500 (c) 900
  37. 37.Best estimate of 863 + 741? (a) 1800 (b) 1600 (c) 1400
  38. 38.Best estimate of 621 + 780? (a) 1200 (b) 1600 (c) 1400
  39. 39.Best estimate of 610 + 191? (a) 600 (b) 1000 (c) 800
  40. 40.Best estimate of 44 × 86? (a) 360 (b) 3600 (c) 36000

Answer key

  1. 1500
  2. 1500
  3. 400
  4. 1000
  5. 400
  6. 2700
  7. 2000
  8. 3500
  9. 900
  10. 1100
  11. 900
  12. 1800
  13. 900
  14. 1200
  15. 4500
  16. 1400
  17. 900
  18. 3000
  19. 3000
  20. 1000
  21. 1200
  22. 1000
  23. 700
  24. 2700
  25. 1800
  26. 1000
  27. 1100
  28. 1000
  29. 7200
  30. 1100
  31. 10000
  32. 900
  33. 600
  34. 200
  35. 1500
  36. 700
  37. 1600
  38. 1400
  39. 800
  40. 3600

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