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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 152 · 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 58 × 84? (a) 4800 (b) 480 (c) 48000
  2. 2.Best estimate of 33 × 31? (a) 9000 (b) 90 (c) 900
  3. 3.Best estimate of 46 × 72? (a) 350 (b) 35000 (c) 3500
  4. 4.Best estimate of 692 + 857? (a) 1400 (b) 1800 (c) 1600
  5. 5.Best estimate of 244 + 655? (a) 700 (b) 1100 (c) 900
  6. 6.Best estimate of 674 + 748? (a) 1200 (b) 1600 (c) 1400
  7. 7.Best estimate of 53 × 21? (a) 10000 (b) 1000 (c) 100
  8. 8.Best estimate of 40 × 12? (a) 4000 (b) 400 (c) 40
  9. 9.Best estimate of 54 × 27? (a) 15000 (b) 1500 (c) 150
  10. 10.Best estimate of 60 × 76? (a) 48000 (b) 480 (c) 4800
  11. 11.Best estimate of 24 × 71? (a) 1400 (b) 14000 (c) 140
  12. 12.Best estimate of 789 + 122? (a) 1100 (b) 900 (c) 700
  13. 13.Best estimate of 83 × 57? (a) 480 (b) 4800 (c) 48000
  14. 14.Best estimate of 86 × 93? (a) 8100 (b) 81000 (c) 810
  15. 15.Best estimate of 228 + 755? (a) 1200 (b) 1000 (c) 800
  16. 16.Best estimate of 835 + 703? (a) 1500 (b) 1700 (c) 1300
  17. 17.Best estimate of 295 + 656? (a) 1000 (b) 1200 (c) 800
  18. 18.Best estimate of 46 × 30? (a) 1500 (b) 150 (c) 15000
  19. 19.Best estimate of 130 + 227? (a) 100 (b) 300 (c) 500
  20. 20.Best estimate of 680 + 479? (a) 1000 (b) 1400 (c) 1200
  21. 21.Best estimate of 325 + 353? (a) 500 (b) 900 (c) 700
  22. 22.Best estimate of 76 × 79? (a) 64000 (b) 6400 (c) 640
  23. 23.Best estimate of 619 + 749? (a) 1100 (b) 1300 (c) 1500
  24. 24.Best estimate of 16 × 60? (a) 120 (b) 1200 (c) 12000
  25. 25.Best estimate of 64 × 41? (a) 24000 (b) 2400 (c) 240
  26. 26.Best estimate of 24 × 89? (a) 180 (b) 18000 (c) 1800
  27. 27.Best estimate of 628 + 290? (a) 700 (b) 900 (c) 1100
  28. 28.Best estimate of 81 × 63? (a) 480 (b) 4800 (c) 48000
  29. 29.Best estimate of 801 + 161? (a) 800 (b) 1200 (c) 1000
  30. 30.Best estimate of 438 + 197? (a) 600 (b) 400 (c) 800
  31. 31.Best estimate of 621 + 754? (a) 1600 (b) 1400 (c) 1200
  32. 32.Best estimate of 33 × 36? (a) 120 (b) 1200 (c) 12000
  33. 33.Best estimate of 59 × 49? (a) 30000 (b) 300 (c) 3000
  34. 34.Best estimate of 90 × 36? (a) 3600 (b) 360 (c) 36000
  35. 35.Best estimate of 729 + 728? (a) 1400 (b) 1600 (c) 1200
  36. 36.Best estimate of 28 × 86? (a) 270 (b) 27000 (c) 2700
  37. 37.Best estimate of 70 × 69? (a) 4900 (b) 49000 (c) 490
  38. 38.Best estimate of 22 × 16? (a) 40 (b) 400 (c) 4000
  39. 39.Best estimate of 27 × 12? (a) 3000 (b) 300 (c) 30
  40. 40.Best estimate of 378 + 412? (a) 800 (b) 600 (c) 1000

Answer key

  1. 4800
  2. 900
  3. 3500
  4. 1600
  5. 900
  6. 1400
  7. 1000
  8. 400
  9. 1500
  10. 4800
  11. 1400
  12. 900
  13. 4800
  14. 8100
  15. 1000
  16. 1500
  17. 1000
  18. 1500
  19. 300
  20. 1200
  21. 700
  22. 6400
  23. 1300
  24. 1200
  25. 2400
  26. 1800
  27. 900
  28. 4800
  29. 1000
  30. 600
  31. 1400
  32. 1200
  33. 3000
  34. 3600
  35. 1400
  36. 2700
  37. 4900
  38. 400
  39. 300
  40. 800

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