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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 621 · 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 871 + 517? (a) 1600 (b) 1200 (c) 1400
  2. 2.Best estimate of 81 × 73? (a) 56000 (b) 560 (c) 5600
  3. 3.Best estimate of 572 + 228? (a) 600 (b) 1000 (c) 800
  4. 4.Best estimate of 31 × 31? (a) 9000 (b) 900 (c) 90
  5. 5.Best estimate of 71 × 26? (a) 21000 (b) 2100 (c) 210
  6. 6.Best estimate of 706 + 566? (a) 1300 (b) 1500 (c) 1100
  7. 7.Best estimate of 28 × 46? (a) 15000 (b) 1500 (c) 150
  8. 8.Best estimate of 54 × 36? (a) 2000 (b) 20000 (c) 200
  9. 9.Best estimate of 739 + 744? (a) 1400 (b) 1600 (c) 1200
  10. 10.Best estimate of 274 + 238? (a) 500 (b) 700 (c) 300
  11. 11.Best estimate of 56 × 24? (a) 1200 (b) 120 (c) 12000
  12. 12.Best estimate of 321 + 812? (a) 1300 (b) 1100 (c) 900
  13. 13.Best estimate of 460 + 796? (a) 1100 (b) 1300 (c) 1500
  14. 14.Best estimate of 79 × 61? (a) 4800 (b) 48000 (c) 480
  15. 15.Best estimate of 17 × 81? (a) 160 (b) 1600 (c) 16000
  16. 16.Best estimate of 98 × 27? (a) 300 (b) 30000 (c) 3000
  17. 17.Best estimate of 96 × 53? (a) 500 (b) 50000 (c) 5000
  18. 18.Best estimate of 26 × 81? (a) 240 (b) 24000 (c) 2400
  19. 19.Best estimate of 48 × 27? (a) 150 (b) 1500 (c) 15000
  20. 20.Best estimate of 686 + 126? (a) 600 (b) 1000 (c) 800
  21. 21.Best estimate of 46 × 82? (a) 400 (b) 4000 (c) 40000
  22. 22.Best estimate of 617 + 683? (a) 1500 (b) 1300 (c) 1100
  23. 23.Best estimate of 27 × 23? (a) 60 (b) 600 (c) 6000
  24. 24.Best estimate of 16 × 60? (a) 12000 (b) 120 (c) 1200
  25. 25.Best estimate of 339 + 223? (a) 300 (b) 500 (c) 700
  26. 26.Best estimate of 809 + 508? (a) 1300 (b) 1500 (c) 1100
  27. 27.Best estimate of 48 × 46? (a) 25000 (b) 2500 (c) 250
  28. 28.Best estimate of 39 × 92? (a) 36000 (b) 3600 (c) 360
  29. 29.Best estimate of 12 × 83? (a) 8000 (b) 800 (c) 80
  30. 30.Best estimate of 213 + 323? (a) 700 (b) 500 (c) 300
  31. 31.Best estimate of 46 × 26? (a) 150 (b) 1500 (c) 15000
  32. 32.Best estimate of 641 + 442? (a) 1200 (b) 800 (c) 1000
  33. 33.Best estimate of 654 + 435? (a) 1100 (b) 1300 (c) 900
  34. 34.Best estimate of 31 × 36? (a) 120 (b) 1200 (c) 12000
  35. 35.Best estimate of 413 + 287? (a) 700 (b) 500 (c) 900
  36. 36.Best estimate of 39 × 14? (a) 4000 (b) 40 (c) 400
  37. 37.Best estimate of 689 + 336? (a) 1000 (b) 1200 (c) 800
  38. 38.Best estimate of 211 + 631? (a) 1000 (b) 800 (c) 600
  39. 39.Best estimate of 39 × 82? (a) 32000 (b) 320 (c) 3200
  40. 40.Best estimate of 29 × 16? (a) 60 (b) 6000 (c) 600

Answer key

  1. 1400
  2. 5600
  3. 800
  4. 900
  5. 2100
  6. 1300
  7. 1500
  8. 2000
  9. 1400
  10. 500
  11. 1200
  12. 1100
  13. 1300
  14. 4800
  15. 1600
  16. 3000
  17. 5000
  18. 2400
  19. 1500
  20. 800
  21. 4000
  22. 1300
  23. 600
  24. 1200
  25. 500
  26. 1300
  27. 2500
  28. 3600
  29. 800
  30. 500
  31. 1500
  32. 1000
  33. 1100
  34. 1200
  35. 700
  36. 400
  37. 1000
  38. 800
  39. 3200
  40. 600

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