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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 187 · 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 171 + 519? (a) 700 (b) 900 (c) 500
  2. 2.Best estimate of 73 × 42? (a) 28000 (b) 280 (c) 2800
  3. 3.Best estimate of 52 × 56? (a) 30000 (b) 300 (c) 3000
  4. 4.Best estimate of 360 + 312? (a) 900 (b) 700 (c) 500
  5. 5.Best estimate of 91 × 98? (a) 90000 (b) 9000 (c) 900
  6. 6.Best estimate of 66 × 21? (a) 1400 (b) 140 (c) 14000
  7. 7.Best estimate of 28 × 28? (a) 9000 (b) 90 (c) 900
  8. 8.Best estimate of 724 + 141? (a) 1000 (b) 800 (c) 600
  9. 9.Best estimate of 60 × 74? (a) 420 (b) 42000 (c) 4200
  10. 10.Best estimate of 549 + 774? (a) 1500 (b) 1300 (c) 1100
  11. 11.Best estimate of 340 + 591? (a) 700 (b) 900 (c) 1100
  12. 12.Best estimate of 395 + 815? (a) 1000 (b) 1400 (c) 1200
  13. 13.Best estimate of 51 × 42? (a) 20000 (b) 2000 (c) 200
  14. 14.Best estimate of 699 + 339? (a) 1000 (b) 800 (c) 1200
  15. 15.Best estimate of 30 × 47? (a) 150 (b) 1500 (c) 15000
  16. 16.Best estimate of 82 × 59? (a) 48000 (b) 4800 (c) 480
  17. 17.Best estimate of 552 + 172? (a) 1000 (b) 800 (c) 600
  18. 18.Best estimate of 841 + 746? (a) 1300 (b) 1700 (c) 1500
  19. 19.Best estimate of 480 + 559? (a) 1300 (b) 1100 (c) 900
  20. 20.Best estimate of 692 + 367? (a) 1300 (b) 900 (c) 1100
  21. 21.Best estimate of 30 × 86? (a) 27000 (b) 270 (c) 2700
  22. 22.Best estimate of 46 × 77? (a) 40000 (b) 4000 (c) 400
  23. 23.Best estimate of 167 + 322? (a) 500 (b) 700 (c) 300
  24. 24.Best estimate of 875 + 719? (a) 1600 (b) 1800 (c) 1400
  25. 25.Best estimate of 320 + 506? (a) 1000 (b) 800 (c) 600
  26. 26.Best estimate of 73 × 41? (a) 280 (b) 2800 (c) 28000
  27. 27.Best estimate of 22 × 67? (a) 14000 (b) 1400 (c) 140
  28. 28.Best estimate of 38 × 29? (a) 12000 (b) 1200 (c) 120
  29. 29.Best estimate of 33 × 52? (a) 15000 (b) 150 (c) 1500
  30. 30.Best estimate of 731 + 636? (a) 1500 (b) 1300 (c) 1100
  31. 31.Best estimate of 46 × 79? (a) 40000 (b) 400 (c) 4000
  32. 32.Best estimate of 81 × 32? (a) 24000 (b) 2400 (c) 240
  33. 33.Best estimate of 86 × 41? (a) 3600 (b) 36000 (c) 360
  34. 34.Best estimate of 84 × 61? (a) 480 (b) 4800 (c) 48000
  35. 35.Best estimate of 690 + 341? (a) 1000 (b) 800 (c) 1200
  36. 36.Best estimate of 36 × 31? (a) 1200 (b) 12000 (c) 120
  37. 37.Best estimate of 88 × 80? (a) 720 (b) 7200 (c) 72000
  38. 38.Best estimate of 304 + 644? (a) 700 (b) 1100 (c) 900
  39. 39.Best estimate of 51 × 56? (a) 30000 (b) 3000 (c) 300
  40. 40.Best estimate of 39 × 21? (a) 800 (b) 80 (c) 8000

Answer key

  1. 700
  2. 2800
  3. 3000
  4. 700
  5. 9000
  6. 1400
  7. 900
  8. 800
  9. 4200
  10. 1300
  11. 900
  12. 1200
  13. 2000
  14. 1000
  15. 1500
  16. 4800
  17. 800
  18. 1500
  19. 1100
  20. 1100
  21. 2700
  22. 4000
  23. 500
  24. 1600
  25. 800
  26. 2800
  27. 1400
  28. 1200
  29. 1500
  30. 1300
  31. 4000
  32. 2400
  33. 3600
  34. 4800
  35. 1000
  36. 1200
  37. 7200
  38. 900
  39. 3000
  40. 800

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