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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 787 · 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 48 × 29? (a) 15000 (b) 1500 (c) 150
  2. 2.Best estimate of 51 × 78? (a) 40000 (b) 400 (c) 4000
  3. 3.Best estimate of 57 × 93? (a) 5400 (b) 54000 (c) 540
  4. 4.Best estimate of 154 + 578? (a) 1000 (b) 800 (c) 600
  5. 5.Best estimate of 93 × 16? (a) 1800 (b) 18000 (c) 180
  6. 6.Best estimate of 79 × 68? (a) 5600 (b) 56000 (c) 560
  7. 7.Best estimate of 286 + 495? (a) 800 (b) 1000 (c) 600
  8. 8.Best estimate of 17 × 57? (a) 1200 (b) 12000 (c) 120
  9. 9.Best estimate of 92 × 46? (a) 450 (b) 45000 (c) 4500
  10. 10.Best estimate of 74 × 18? (a) 14000 (b) 140 (c) 1400
  11. 11.Best estimate of 128 + 512? (a) 400 (b) 600 (c) 800
  12. 12.Best estimate of 91 × 29? (a) 2700 (b) 27000 (c) 270
  13. 13.Best estimate of 81 × 74? (a) 56000 (b) 5600 (c) 560
  14. 14.Best estimate of 743 + 489? (a) 1200 (b) 1000 (c) 1400
  15. 15.Best estimate of 24 × 14? (a) 200 (b) 20 (c) 2000
  16. 16.Best estimate of 90 × 56? (a) 5400 (b) 540 (c) 54000
  17. 17.Best estimate of 39 × 57? (a) 2400 (b) 240 (c) 24000
  18. 18.Best estimate of 166 + 130? (a) 100 (b) 500 (c) 300
  19. 19.Best estimate of 29 × 70? (a) 210 (b) 2100 (c) 21000
  20. 20.Best estimate of 72 × 16? (a) 140 (b) 14000 (c) 1400
  21. 21.Best estimate of 76 × 63? (a) 4800 (b) 480 (c) 48000
  22. 22.Best estimate of 158 + 415? (a) 800 (b) 400 (c) 600
  23. 23.Best estimate of 641 + 160? (a) 800 (b) 600 (c) 1000
  24. 24.Best estimate of 72 × 21? (a) 1400 (b) 14000 (c) 140
  25. 25.Best estimate of 320 + 513? (a) 1000 (b) 600 (c) 800
  26. 26.Best estimate of 444 + 446? (a) 800 (b) 600 (c) 1000
  27. 27.Best estimate of 28 × 94? (a) 2700 (b) 27000 (c) 270
  28. 28.Best estimate of 830 + 148? (a) 900 (b) 1100 (c) 700
  29. 29.Best estimate of 91 × 76? (a) 720 (b) 72000 (c) 7200
  30. 30.Best estimate of 32 × 86? (a) 27000 (b) 2700 (c) 270
  31. 31.Best estimate of 47 × 92? (a) 45000 (b) 4500 (c) 450
  32. 32.Best estimate of 76 × 96? (a) 800 (b) 80000 (c) 8000
  33. 33.Best estimate of 176 + 273? (a) 300 (b) 700 (c) 500
  34. 34.Best estimate of 854 + 641? (a) 1500 (b) 1300 (c) 1700
  35. 35.Best estimate of 76 × 31? (a) 240 (b) 24000 (c) 2400
  36. 36.Best estimate of 36 × 36? (a) 1600 (b) 160 (c) 16000
  37. 37.Best estimate of 303 + 214? (a) 500 (b) 700 (c) 300
  38. 38.Best estimate of 73 × 78? (a) 5600 (b) 56000 (c) 560
  39. 39.Best estimate of 33 × 92? (a) 2700 (b) 27000 (c) 270
  40. 40.Best estimate of 677 + 346? (a) 800 (b) 1000 (c) 1200

Answer key

  1. 1500
  2. 4000
  3. 5400
  4. 800
  5. 1800
  6. 5600
  7. 800
  8. 1200
  9. 4500
  10. 1400
  11. 600
  12. 2700
  13. 5600
  14. 1200
  15. 200
  16. 5400
  17. 2400
  18. 300
  19. 2100
  20. 1400
  21. 4800
  22. 600
  23. 800
  24. 1400
  25. 800
  26. 800
  27. 2700
  28. 900
  29. 7200
  30. 2700
  31. 4500
  32. 8000
  33. 500
  34. 1500
  35. 2400
  36. 1600
  37. 500
  38. 5600
  39. 2700
  40. 1000

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