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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 934 · 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 46 × 91? (a) 45000 (b) 4500 (c) 450
  2. 2.Best estimate of 64 × 40? (a) 240 (b) 24000 (c) 2400
  3. 3.Best estimate of 90 × 26? (a) 2700 (b) 27000 (c) 270
  4. 4.Best estimate of 42 × 77? (a) 32000 (b) 320 (c) 3200
  5. 5.Best estimate of 735 + 403? (a) 900 (b) 1300 (c) 1100
  6. 6.Best estimate of 27 × 46? (a) 1500 (b) 15000 (c) 150
  7. 7.Best estimate of 594 + 788? (a) 1600 (b) 1200 (c) 1400
  8. 8.Best estimate of 56 × 36? (a) 240 (b) 24000 (c) 2400
  9. 9.Best estimate of 308 + 834? (a) 1100 (b) 1300 (c) 900
  10. 10.Best estimate of 16 × 46? (a) 10000 (b) 100 (c) 1000
  11. 11.Best estimate of 800 + 817? (a) 1600 (b) 1800 (c) 1400
  12. 12.Best estimate of 242 + 734? (a) 1100 (b) 700 (c) 900
  13. 13.Best estimate of 12 × 36? (a) 40 (b) 4000 (c) 400
  14. 14.Best estimate of 773 + 671? (a) 1300 (b) 1500 (c) 1700
  15. 15.Best estimate of 90 × 92? (a) 81000 (b) 810 (c) 8100
  16. 16.Best estimate of 67 × 33? (a) 210 (b) 2100 (c) 21000
  17. 17.Best estimate of 44 × 26? (a) 12000 (b) 1200 (c) 120
  18. 18.Best estimate of 66 × 26? (a) 21000 (b) 210 (c) 2100
  19. 19.Best estimate of 47 × 13? (a) 5000 (b) 50 (c) 500
  20. 20.Best estimate of 14 × 67? (a) 7000 (b) 700 (c) 70
  21. 21.Best estimate of 300 + 820? (a) 1100 (b) 1300 (c) 900
  22. 22.Best estimate of 838 + 327? (a) 1100 (b) 1300 (c) 900
  23. 23.Best estimate of 487 + 580? (a) 900 (b) 1100 (c) 1300
  24. 24.Best estimate of 46 × 33? (a) 15000 (b) 1500 (c) 150
  25. 25.Best estimate of 71 × 19? (a) 140 (b) 1400 (c) 14000
  26. 26.Best estimate of 629 + 373? (a) 1200 (b) 800 (c) 1000
  27. 27.Best estimate of 18 × 92? (a) 1800 (b) 18000 (c) 180
  28. 28.Best estimate of 89 × 80? (a) 7200 (b) 72000 (c) 720
  29. 29.Best estimate of 70 × 86? (a) 6300 (b) 630 (c) 63000
  30. 30.Best estimate of 82 × 88? (a) 7200 (b) 720 (c) 72000
  31. 31.Best estimate of 43 × 76? (a) 320 (b) 3200 (c) 32000
  32. 32.Best estimate of 424 + 273? (a) 900 (b) 700 (c) 500
  33. 33.Best estimate of 14 × 44? (a) 40 (b) 400 (c) 4000
  34. 34.Best estimate of 447 + 545? (a) 700 (b) 900 (c) 1100
  35. 35.Best estimate of 660 + 420? (a) 1300 (b) 1100 (c) 900
  36. 36.Best estimate of 857 + 154? (a) 900 (b) 1100 (c) 1300
  37. 37.Best estimate of 653 + 696? (a) 1600 (b) 1200 (c) 1400
  38. 38.Best estimate of 664 + 465? (a) 1200 (b) 1400 (c) 1000
  39. 39.Best estimate of 67 × 97? (a) 70000 (b) 700 (c) 7000
  40. 40.Best estimate of 29 × 69? (a) 21000 (b) 210 (c) 2100

Answer key

  1. 4500
  2. 2400
  3. 2700
  4. 3200
  5. 1100
  6. 1500
  7. 1400
  8. 2400
  9. 1100
  10. 1000
  11. 1600
  12. 900
  13. 400
  14. 1500
  15. 8100
  16. 2100
  17. 1200
  18. 2100
  19. 500
  20. 700
  21. 1100
  22. 1100
  23. 1100
  24. 1500
  25. 1400
  26. 1000
  27. 1800
  28. 7200
  29. 6300
  30. 7200
  31. 3200
  32. 700
  33. 400
  34. 900
  35. 1100
  36. 1100
  37. 1400
  38. 1200
  39. 7000
  40. 2100

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