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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 784 · 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 419 + 539? (a) 1100 (b) 900 (c) 700
  2. 2.Best estimate of 624 + 533? (a) 1300 (b) 900 (c) 1100
  3. 3.Best estimate of 260 + 156? (a) 300 (b) 700 (c) 500
  4. 4.Best estimate of 178 + 192? (a) 600 (b) 200 (c) 400
  5. 5.Best estimate of 255 + 865? (a) 1000 (b) 1200 (c) 1400
  6. 6.Best estimate of 581 + 456? (a) 1300 (b) 900 (c) 1100
  7. 7.Best estimate of 806 + 236? (a) 1000 (b) 800 (c) 1200
  8. 8.Best estimate of 76 × 27? (a) 240 (b) 24000 (c) 2400
  9. 9.Best estimate of 508 + 226? (a) 700 (b) 900 (c) 500
  10. 10.Best estimate of 83 × 27? (a) 2400 (b) 240 (c) 24000
  11. 11.Best estimate of 27 × 30? (a) 9000 (b) 90 (c) 900
  12. 12.Best estimate of 366 + 774? (a) 1200 (b) 1400 (c) 1000
  13. 13.Best estimate of 12 × 22? (a) 2000 (b) 20 (c) 200
  14. 14.Best estimate of 82 × 56? (a) 4800 (b) 480 (c) 48000
  15. 15.Best estimate of 448 + 272? (a) 700 (b) 900 (c) 500
  16. 16.Best estimate of 46 × 23? (a) 100 (b) 1000 (c) 10000
  17. 17.Best estimate of 768 + 669? (a) 1500 (b) 1300 (c) 1700
  18. 18.Best estimate of 61 × 13? (a) 6000 (b) 600 (c) 60
  19. 19.Best estimate of 36 × 77? (a) 3200 (b) 320 (c) 32000
  20. 20.Best estimate of 644 + 574? (a) 1400 (b) 1200 (c) 1000
  21. 21.Best estimate of 23 × 41? (a) 800 (b) 8000 (c) 80
  22. 22.Best estimate of 51 × 61? (a) 300 (b) 3000 (c) 30000
  23. 23.Best estimate of 29 × 56? (a) 1800 (b) 180 (c) 18000
  24. 24.Best estimate of 67 × 83? (a) 560 (b) 56000 (c) 5600
  25. 25.Best estimate of 490 + 587? (a) 900 (b) 1300 (c) 1100
  26. 26.Best estimate of 660 + 497? (a) 1200 (b) 1400 (c) 1000
  27. 27.Best estimate of 48 × 76? (a) 40000 (b) 4000 (c) 400
  28. 28.Best estimate of 97 × 32? (a) 300 (b) 3000 (c) 30000
  29. 29.Best estimate of 28 × 36? (a) 1200 (b) 12000 (c) 120
  30. 30.Best estimate of 498 + 781? (a) 1300 (b) 1500 (c) 1100
  31. 31.Best estimate of 47 × 50? (a) 250 (b) 25000 (c) 2500
  32. 32.Best estimate of 12 × 33? (a) 300 (b) 30 (c) 3000
  33. 33.Best estimate of 831 + 610? (a) 1200 (b) 1400 (c) 1600
  34. 34.Best estimate of 380 + 155? (a) 800 (b) 600 (c) 400
  35. 35.Best estimate of 52 × 60? (a) 300 (b) 3000 (c) 30000
  36. 36.Best estimate of 26 × 80? (a) 24000 (b) 240 (c) 2400
  37. 37.Best estimate of 29 × 69? (a) 21000 (b) 2100 (c) 210
  38. 38.Best estimate of 62 × 93? (a) 54000 (b) 5400 (c) 540
  39. 39.Best estimate of 589 + 576? (a) 1200 (b) 1000 (c) 1400
  40. 40.Best estimate of 82 × 50? (a) 4000 (b) 400 (c) 40000

Answer key

  1. 900
  2. 1100
  3. 500
  4. 400
  5. 1200
  6. 1100
  7. 1000
  8. 2400
  9. 700
  10. 2400
  11. 900
  12. 1200
  13. 200
  14. 4800
  15. 700
  16. 1000
  17. 1500
  18. 600
  19. 3200
  20. 1200
  21. 800
  22. 3000
  23. 1800
  24. 5600
  25. 1100
  26. 1200
  27. 4000
  28. 3000
  29. 1200
  30. 1300
  31. 2500
  32. 300
  33. 1400
  34. 600
  35. 3000
  36. 2400
  37. 2100
  38. 5400
  39. 1200
  40. 4000

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