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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 93 · 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 253 + 266? (a) 600 (b) 400 (c) 800
  2. 2.Best estimate of 403 + 847? (a) 1400 (b) 1200 (c) 1000
  3. 3.Best estimate of 69 × 90? (a) 6300 (b) 63000 (c) 630
  4. 4.Best estimate of 46 × 31? (a) 1500 (b) 15000 (c) 150
  5. 5.Best estimate of 170 + 691? (a) 700 (b) 1100 (c) 900
  6. 6.Best estimate of 838 + 400? (a) 1000 (b) 1400 (c) 1200
  7. 7.Best estimate of 352 + 335? (a) 900 (b) 500 (c) 700
  8. 8.Best estimate of 44 × 26? (a) 1200 (b) 120 (c) 12000
  9. 9.Best estimate of 13 × 70? (a) 70 (b) 700 (c) 7000
  10. 10.Best estimate of 63 × 89? (a) 540 (b) 5400 (c) 54000
  11. 11.Best estimate of 820 + 568? (a) 1600 (b) 1400 (c) 1200
  12. 12.Best estimate of 50 × 41? (a) 200 (b) 20000 (c) 2000
  13. 13.Best estimate of 751 + 841? (a) 1800 (b) 1600 (c) 1400
  14. 14.Best estimate of 652 + 281? (a) 1000 (b) 800 (c) 1200
  15. 15.Best estimate of 89 × 39? (a) 36000 (b) 3600 (c) 360
  16. 16.Best estimate of 42 × 33? (a) 1200 (b) 12000 (c) 120
  17. 17.Best estimate of 148 + 562? (a) 700 (b) 900 (c) 500
  18. 18.Best estimate of 96 × 70? (a) 7000 (b) 70000 (c) 700
  19. 19.Best estimate of 58 × 36? (a) 2400 (b) 24000 (c) 240
  20. 20.Best estimate of 687 + 472? (a) 1400 (b) 1200 (c) 1000
  21. 21.Best estimate of 215 + 274? (a) 300 (b) 700 (c) 500
  22. 22.Best estimate of 63 × 39? (a) 24000 (b) 240 (c) 2400
  23. 23.Best estimate of 202 + 462? (a) 700 (b) 500 (c) 900
  24. 24.Best estimate of 59 × 76? (a) 48000 (b) 4800 (c) 480
  25. 25.Best estimate of 720 + 875? (a) 1600 (b) 1800 (c) 1400
  26. 26.Best estimate of 313 + 531? (a) 800 (b) 1000 (c) 600
  27. 27.Best estimate of 86 × 17? (a) 18000 (b) 180 (c) 1800
  28. 28.Best estimate of 771 + 223? (a) 1000 (b) 800 (c) 1200
  29. 29.Best estimate of 613 + 656? (a) 1100 (b) 1300 (c) 1500
  30. 30.Best estimate of 339 + 240? (a) 500 (b) 700 (c) 300
  31. 31.Best estimate of 88 × 30? (a) 270 (b) 27000 (c) 2700
  32. 32.Best estimate of 14 × 46? (a) 5000 (b) 50 (c) 500
  33. 33.Best estimate of 61 × 33? (a) 180 (b) 1800 (c) 18000
  34. 34.Best estimate of 331 + 681? (a) 1000 (b) 1200 (c) 800
  35. 35.Best estimate of 594 + 343? (a) 900 (b) 700 (c) 1100
  36. 36.Best estimate of 56 × 71? (a) 4200 (b) 420 (c) 42000
  37. 37.Best estimate of 817 + 231? (a) 1000 (b) 800 (c) 1200
  38. 38.Best estimate of 62 × 72? (a) 420 (b) 42000 (c) 4200
  39. 39.Best estimate of 838 + 123? (a) 1100 (b) 900 (c) 700
  40. 40.Best estimate of 86 × 91? (a) 8100 (b) 81000 (c) 810

Answer key

  1. 600
  2. 1200
  3. 6300
  4. 1500
  5. 900
  6. 1200
  7. 700
  8. 1200
  9. 700
  10. 5400
  11. 1400
  12. 2000
  13. 1600
  14. 1000
  15. 3600
  16. 1200
  17. 700
  18. 7000
  19. 2400
  20. 1200
  21. 500
  22. 2400
  23. 700
  24. 4800
  25. 1600
  26. 800
  27. 1800
  28. 1000
  29. 1300
  30. 500
  31. 2700
  32. 500
  33. 1800
  34. 1000
  35. 900
  36. 4200
  37. 1000
  38. 4200
  39. 900
  40. 8100

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