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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 692 · 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 20 × 50? (a) 1000 (b) 10000 (c) 100
  2. 2.Best estimate of 160 + 321? (a) 300 (b) 700 (c) 500
  3. 3.Best estimate of 375 + 575? (a) 1000 (b) 800 (c) 1200
  4. 4.Best estimate of 201 + 312? (a) 300 (b) 500 (c) 700
  5. 5.Best estimate of 82 × 88? (a) 72000 (b) 720 (c) 7200
  6. 6.Best estimate of 26 × 60? (a) 180 (b) 18000 (c) 1800
  7. 7.Best estimate of 96 × 16? (a) 200 (b) 2000 (c) 20000
  8. 8.Best estimate of 20 × 87? (a) 18000 (b) 1800 (c) 180
  9. 9.Best estimate of 639 + 517? (a) 1300 (b) 900 (c) 1100
  10. 10.Best estimate of 46 × 87? (a) 450 (b) 45000 (c) 4500
  11. 11.Best estimate of 91 × 59? (a) 54000 (b) 5400 (c) 540
  12. 12.Best estimate of 61 × 19? (a) 1200 (b) 12000 (c) 120
  13. 13.Best estimate of 74 × 73? (a) 49000 (b) 4900 (c) 490
  14. 14.Best estimate of 713 + 464? (a) 1200 (b) 1400 (c) 1000
  15. 15.Best estimate of 96 × 87? (a) 9000 (b) 90000 (c) 900
  16. 16.Best estimate of 587 + 424? (a) 800 (b) 1200 (c) 1000
  17. 17.Best estimate of 615 + 708? (a) 1300 (b) 1500 (c) 1100
  18. 18.Best estimate of 871 + 195? (a) 1300 (b) 900 (c) 1100
  19. 19.Best estimate of 50 × 81? (a) 400 (b) 40000 (c) 4000
  20. 20.Best estimate of 24 × 72? (a) 14000 (b) 1400 (c) 140
  21. 21.Best estimate of 56 × 64? (a) 3600 (b) 36000 (c) 360
  22. 22.Best estimate of 528 + 396? (a) 900 (b) 1100 (c) 700
  23. 23.Best estimate of 53 × 23? (a) 100 (b) 10000 (c) 1000
  24. 24.Best estimate of 98 × 13? (a) 10000 (b) 1000 (c) 100
  25. 25.Best estimate of 36 × 63? (a) 2400 (b) 24000 (c) 240
  26. 26.Best estimate of 14 × 81? (a) 80 (b) 800 (c) 8000
  27. 27.Best estimate of 34 × 54? (a) 1500 (b) 150 (c) 15000
  28. 28.Best estimate of 17 × 32? (a) 600 (b) 6000 (c) 60
  29. 29.Best estimate of 29 × 26? (a) 9000 (b) 900 (c) 90
  30. 30.Best estimate of 711 + 798? (a) 1500 (b) 1300 (c) 1700
  31. 31.Best estimate of 767 + 483? (a) 1500 (b) 1100 (c) 1300
  32. 32.Best estimate of 88 × 19? (a) 180 (b) 18000 (c) 1800
  33. 33.Best estimate of 785 + 304? (a) 1300 (b) 1100 (c) 900
  34. 34.Best estimate of 767 + 272? (a) 1300 (b) 1100 (c) 900
  35. 35.Best estimate of 66 × 30? (a) 210 (b) 21000 (c) 2100
  36. 36.Best estimate of 31 × 73? (a) 2100 (b) 210 (c) 21000
  37. 37.Best estimate of 721 + 194? (a) 700 (b) 900 (c) 1100
  38. 38.Best estimate of 90 × 61? (a) 5400 (b) 54000 (c) 540
  39. 39.Best estimate of 610 + 806? (a) 1200 (b) 1600 (c) 1400
  40. 40.Best estimate of 72 × 58? (a) 42000 (b) 4200 (c) 420

Answer key

  1. 1000
  2. 500
  3. 1000
  4. 500
  5. 7200
  6. 1800
  7. 2000
  8. 1800
  9. 1100
  10. 4500
  11. 5400
  12. 1200
  13. 4900
  14. 1200
  15. 9000
  16. 1000
  17. 1300
  18. 1100
  19. 4000
  20. 1400
  21. 3600
  22. 900
  23. 1000
  24. 1000
  25. 2400
  26. 800
  27. 1500
  28. 600
  29. 900
  30. 1500
  31. 1300
  32. 1800
  33. 1100
  34. 1100
  35. 2100
  36. 2100
  37. 900
  38. 5400
  39. 1400
  40. 4200

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