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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 815 · 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 50 × 27? (a) 1500 (b) 15000 (c) 150
  2. 2.Best estimate of 225 + 176? (a) 600 (b) 400 (c) 200
  3. 3.Best estimate of 642 + 651? (a) 1100 (b) 1500 (c) 1300
  4. 4.Best estimate of 59 × 66? (a) 4200 (b) 42000 (c) 420
  5. 5.Best estimate of 692 + 532? (a) 1400 (b) 1200 (c) 1000
  6. 6.Best estimate of 358 + 593? (a) 800 (b) 1000 (c) 1200
  7. 7.Best estimate of 26 × 51? (a) 1500 (b) 150 (c) 15000
  8. 8.Best estimate of 566 + 709? (a) 1500 (b) 1300 (c) 1100
  9. 9.Best estimate of 44 × 91? (a) 3600 (b) 36000 (c) 360
  10. 10.Best estimate of 23 × 84? (a) 160 (b) 16000 (c) 1600
  11. 11.Best estimate of 82 × 62? (a) 4800 (b) 48000 (c) 480
  12. 12.Best estimate of 59 × 31? (a) 18000 (b) 1800 (c) 180
  13. 13.Best estimate of 91 × 86? (a) 81000 (b) 8100 (c) 810
  14. 14.Best estimate of 61 × 68? (a) 4200 (b) 42000 (c) 420
  15. 15.Best estimate of 26 × 29? (a) 90 (b) 9000 (c) 900
  16. 16.Best estimate of 52 × 54? (a) 250 (b) 2500 (c) 25000
  17. 17.Best estimate of 58 × 69? (a) 4200 (b) 420 (c) 42000
  18. 18.Best estimate of 570 + 372? (a) 1200 (b) 1000 (c) 800
  19. 19.Best estimate of 169 + 228? (a) 200 (b) 600 (c) 400
  20. 20.Best estimate of 27 × 29? (a) 900 (b) 9000 (c) 90
  21. 21.Best estimate of 51 × 31? (a) 1500 (b) 150 (c) 15000
  22. 22.Best estimate of 353 + 617? (a) 1200 (b) 1000 (c) 800
  23. 23.Best estimate of 32 × 36? (a) 12000 (b) 120 (c) 1200
  24. 24.Best estimate of 40 × 27? (a) 12000 (b) 1200 (c) 120
  25. 25.Best estimate of 38 × 16? (a) 80 (b) 8000 (c) 800
  26. 26.Best estimate of 30 × 16? (a) 6000 (b) 60 (c) 600
  27. 27.Best estimate of 308 + 594? (a) 900 (b) 700 (c) 1100
  28. 28.Best estimate of 855 + 839? (a) 1900 (b) 1500 (c) 1700
  29. 29.Best estimate of 810 + 665? (a) 1700 (b) 1500 (c) 1300
  30. 30.Best estimate of 351 + 590? (a) 1000 (b) 800 (c) 1200
  31. 31.Best estimate of 34 × 67? (a) 2100 (b) 210 (c) 21000
  32. 32.Best estimate of 668 + 863? (a) 1600 (b) 1400 (c) 1800
  33. 33.Best estimate of 667 + 585? (a) 1300 (b) 1100 (c) 1500
  34. 34.Best estimate of 38 × 64? (a) 24000 (b) 2400 (c) 240
  35. 35.Best estimate of 378 + 806? (a) 1000 (b) 1400 (c) 1200
  36. 36.Best estimate of 458 + 788? (a) 1500 (b) 1100 (c) 1300
  37. 37.Best estimate of 74 × 78? (a) 5600 (b) 560 (c) 56000
  38. 38.Best estimate of 36 × 14? (a) 400 (b) 40 (c) 4000
  39. 39.Best estimate of 166 + 785? (a) 1200 (b) 800 (c) 1000
  40. 40.Best estimate of 24 × 12? (a) 20 (b) 200 (c) 2000

Answer key

  1. 1500
  2. 400
  3. 1300
  4. 4200
  5. 1200
  6. 1000
  7. 1500
  8. 1300
  9. 3600
  10. 1600
  11. 4800
  12. 1800
  13. 8100
  14. 4200
  15. 900
  16. 2500
  17. 4200
  18. 1000
  19. 400
  20. 900
  21. 1500
  22. 1000
  23. 1200
  24. 1200
  25. 800
  26. 600
  27. 900
  28. 1700
  29. 1500
  30. 1000
  31. 2100
  32. 1600
  33. 1300
  34. 2400
  35. 1200
  36. 1300
  37. 5600
  38. 400
  39. 1000
  40. 200

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