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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 35 · 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 44 × 76? (a) 320 (b) 32000 (c) 3200
  2. 2.Best estimate of 224 + 140? (a) 100 (b) 300 (c) 500
  3. 3.Best estimate of 714 + 289? (a) 1200 (b) 1000 (c) 800
  4. 4.Best estimate of 67 × 22? (a) 140 (b) 14000 (c) 1400
  5. 5.Best estimate of 560 + 172? (a) 1000 (b) 600 (c) 800
  6. 6.Best estimate of 602 + 626? (a) 1000 (b) 1200 (c) 1400
  7. 7.Best estimate of 128 + 745? (a) 600 (b) 800 (c) 1000
  8. 8.Best estimate of 49 × 50? (a) 250 (b) 25000 (c) 2500
  9. 9.Best estimate of 197 + 155? (a) 400 (b) 200 (c) 600
  10. 10.Best estimate of 38 × 79? (a) 3200 (b) 320 (c) 32000
  11. 11.Best estimate of 798 + 593? (a) 1200 (b) 1600 (c) 1400
  12. 12.Best estimate of 40 × 30? (a) 1200 (b) 120 (c) 12000
  13. 13.Best estimate of 282 + 844? (a) 900 (b) 1100 (c) 1300
  14. 14.Best estimate of 16 × 60? (a) 12000 (b) 1200 (c) 120
  15. 15.Best estimate of 138 + 502? (a) 400 (b) 800 (c) 600
  16. 16.Best estimate of 26 × 32? (a) 90 (b) 9000 (c) 900
  17. 17.Best estimate of 83 × 94? (a) 7200 (b) 720 (c) 72000
  18. 18.Best estimate of 87 × 20? (a) 180 (b) 1800 (c) 18000
  19. 19.Best estimate of 96 × 86? (a) 9000 (b) 90000 (c) 900
  20. 20.Best estimate of 769 + 223? (a) 1200 (b) 800 (c) 1000
  21. 21.Best estimate of 80 × 61? (a) 4800 (b) 480 (c) 48000
  22. 22.Best estimate of 96 × 93? (a) 9000 (b) 90000 (c) 900
  23. 23.Best estimate of 37 × 16? (a) 800 (b) 8000 (c) 80
  24. 24.Best estimate of 677 + 318? (a) 800 (b) 1000 (c) 1200
  25. 25.Best estimate of 87 × 69? (a) 630 (b) 63000 (c) 6300
  26. 26.Best estimate of 46 × 29? (a) 1500 (b) 15000 (c) 150
  27. 27.Best estimate of 872 + 606? (a) 1500 (b) 1300 (c) 1700
  28. 28.Best estimate of 511 + 873? (a) 1200 (b) 1400 (c) 1600
  29. 29.Best estimate of 201 + 339? (a) 300 (b) 500 (c) 700
  30. 30.Best estimate of 130 + 272? (a) 600 (b) 400 (c) 200
  31. 31.Best estimate of 520 + 582? (a) 1100 (b) 1300 (c) 900
  32. 32.Best estimate of 24 × 96? (a) 200 (b) 20000 (c) 2000
  33. 33.Best estimate of 174 + 420? (a) 800 (b) 400 (c) 600
  34. 34.Best estimate of 56 × 17? (a) 120 (b) 1200 (c) 12000
  35. 35.Best estimate of 464 + 700? (a) 1200 (b) 1000 (c) 1400
  36. 36.Best estimate of 630 + 515? (a) 1100 (b) 1300 (c) 900
  37. 37.Best estimate of 83 × 64? (a) 48000 (b) 4800 (c) 480
  38. 38.Best estimate of 77 × 81? (a) 640 (b) 6400 (c) 64000
  39. 39.Best estimate of 61 × 98? (a) 6000 (b) 60000 (c) 600
  40. 40.Best estimate of 13 × 33? (a) 30 (b) 3000 (c) 300

Answer key

  1. 3200
  2. 300
  3. 1000
  4. 1400
  5. 800
  6. 1200
  7. 800
  8. 2500
  9. 400
  10. 3200
  11. 1400
  12. 1200
  13. 1100
  14. 1200
  15. 600
  16. 900
  17. 7200
  18. 1800
  19. 9000
  20. 1000
  21. 4800
  22. 9000
  23. 800
  24. 1000
  25. 6300
  26. 1500
  27. 1500
  28. 1400
  29. 500
  30. 400
  31. 1100
  32. 2000
  33. 600
  34. 1200
  35. 1200
  36. 1100
  37. 4800
  38. 6400
  39. 6000
  40. 300

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