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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 54 · 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 418 + 771? (a) 1200 (b) 1000 (c) 1400
  2. 2.Best estimate of 76 × 81? (a) 64000 (b) 6400 (c) 640
  3. 3.Best estimate of 517 + 138? (a) 400 (b) 800 (c) 600
  4. 4.Best estimate of 17 × 58? (a) 1200 (b) 12000 (c) 120
  5. 5.Best estimate of 299 + 300? (a) 600 (b) 400 (c) 800
  6. 6.Best estimate of 456 + 397? (a) 700 (b) 900 (c) 1100
  7. 7.Best estimate of 272 + 872? (a) 1400 (b) 1200 (c) 1000
  8. 8.Best estimate of 215 + 147? (a) 100 (b) 300 (c) 500
  9. 9.Best estimate of 662 + 282? (a) 1200 (b) 800 (c) 1000
  10. 10.Best estimate of 16 × 78? (a) 1600 (b) 16000 (c) 160
  11. 11.Best estimate of 462 + 703? (a) 1400 (b) 1000 (c) 1200
  12. 12.Best estimate of 69 × 14? (a) 700 (b) 70 (c) 7000
  13. 13.Best estimate of 58 × 62? (a) 360 (b) 36000 (c) 3600
  14. 14.Best estimate of 67 × 14? (a) 700 (b) 7000 (c) 70
  15. 15.Best estimate of 26 × 97? (a) 300 (b) 3000 (c) 30000
  16. 16.Best estimate of 577 + 606? (a) 1000 (b) 1200 (c) 1400
  17. 17.Best estimate of 63 × 41? (a) 2400 (b) 240 (c) 24000
  18. 18.Best estimate of 60 × 64? (a) 360 (b) 36000 (c) 3600
  19. 19.Best estimate of 298 + 215? (a) 500 (b) 700 (c) 300
  20. 20.Best estimate of 27 × 22? (a) 600 (b) 6000 (c) 60
  21. 21.Best estimate of 28 × 90? (a) 2700 (b) 27000 (c) 270
  22. 22.Best estimate of 26 × 58? (a) 180 (b) 1800 (c) 18000
  23. 23.Best estimate of 42 × 81? (a) 32000 (b) 3200 (c) 320
  24. 24.Best estimate of 287 + 621? (a) 1100 (b) 900 (c) 700
  25. 25.Best estimate of 827 + 517? (a) 1500 (b) 1100 (c) 1300
  26. 26.Best estimate of 87 × 62? (a) 540 (b) 5400 (c) 54000
  27. 27.Best estimate of 63 × 34? (a) 18000 (b) 1800 (c) 180
  28. 28.Best estimate of 563 + 519? (a) 900 (b) 1300 (c) 1100
  29. 29.Best estimate of 67 × 37? (a) 2800 (b) 280 (c) 28000
  30. 30.Best estimate of 32 × 23? (a) 600 (b) 6000 (c) 60
  31. 31.Best estimate of 624 + 784? (a) 1200 (b) 1600 (c) 1400
  32. 32.Best estimate of 29 × 51? (a) 15000 (b) 150 (c) 1500
  33. 33.Best estimate of 97 × 12? (a) 1000 (b) 100 (c) 10000
  34. 34.Best estimate of 43 × 46? (a) 20000 (b) 2000 (c) 200
  35. 35.Best estimate of 67 × 76? (a) 5600 (b) 560 (c) 56000
  36. 36.Best estimate of 27 × 53? (a) 15000 (b) 1500 (c) 150
  37. 37.Best estimate of 91 × 97? (a) 900 (b) 90000 (c) 9000
  38. 38.Best estimate of 23 × 72? (a) 1400 (b) 14000 (c) 140
  39. 39.Best estimate of 59 × 19? (a) 1200 (b) 120 (c) 12000
  40. 40.Best estimate of 62 × 69? (a) 420 (b) 4200 (c) 42000

Answer key

  1. 1200
  2. 6400
  3. 600
  4. 1200
  5. 600
  6. 900
  7. 1200
  8. 300
  9. 1000
  10. 1600
  11. 1200
  12. 700
  13. 3600
  14. 700
  15. 3000
  16. 1200
  17. 2400
  18. 3600
  19. 500
  20. 600
  21. 2700
  22. 1800
  23. 3200
  24. 900
  25. 1300
  26. 5400
  27. 1800
  28. 1100
  29. 2800
  30. 600
  31. 1400
  32. 1500
  33. 1000
  34. 2000
  35. 5600
  36. 1500
  37. 9000
  38. 1400
  39. 1200
  40. 4200

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