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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 350 · 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 77 × 50? (a) 40000 (b) 400 (c) 4000
  2. 2.Best estimate of 774 + 427? (a) 1400 (b) 1200 (c) 1000
  3. 3.Best estimate of 555 + 238? (a) 800 (b) 1000 (c) 600
  4. 4.Best estimate of 425 + 304? (a) 700 (b) 500 (c) 900
  5. 5.Best estimate of 512 + 847? (a) 1300 (b) 1500 (c) 1100
  6. 6.Best estimate of 540 + 780? (a) 1500 (b) 1100 (c) 1300
  7. 7.Best estimate of 49 × 86? (a) 4500 (b) 450 (c) 45000
  8. 8.Best estimate of 40 × 36? (a) 1600 (b) 16000 (c) 160
  9. 9.Best estimate of 292 + 804? (a) 1100 (b) 1300 (c) 900
  10. 10.Best estimate of 651 + 170? (a) 1100 (b) 900 (c) 700
  11. 11.Best estimate of 249 + 270? (a) 300 (b) 700 (c) 500
  12. 12.Best estimate of 451 + 384? (a) 700 (b) 1100 (c) 900
  13. 13.Best estimate of 651 + 827? (a) 1700 (b) 1500 (c) 1300
  14. 14.Best estimate of 14 × 41? (a) 4000 (b) 40 (c) 400
  15. 15.Best estimate of 20 × 16? (a) 4000 (b) 40 (c) 400
  16. 16.Best estimate of 39 × 64? (a) 240 (b) 24000 (c) 2400
  17. 17.Best estimate of 497 + 577? (a) 900 (b) 1300 (c) 1100
  18. 18.Best estimate of 39 × 30? (a) 12000 (b) 1200 (c) 120
  19. 19.Best estimate of 47 × 16? (a) 1000 (b) 10000 (c) 100
  20. 20.Best estimate of 37 × 54? (a) 20000 (b) 2000 (c) 200
  21. 21.Best estimate of 869 + 470? (a) 1400 (b) 1200 (c) 1600
  22. 22.Best estimate of 68 × 36? (a) 2800 (b) 280 (c) 28000
  23. 23.Best estimate of 863 + 769? (a) 1700 (b) 1900 (c) 1500
  24. 24.Best estimate of 82 × 46? (a) 400 (b) 4000 (c) 40000
  25. 25.Best estimate of 47 × 56? (a) 300 (b) 30000 (c) 3000
  26. 26.Best estimate of 36 × 27? (a) 1200 (b) 120 (c) 12000
  27. 27.Best estimate of 36 × 30? (a) 1200 (b) 12000 (c) 120
  28. 28.Best estimate of 98 × 50? (a) 500 (b) 50000 (c) 5000
  29. 29.Best estimate of 600 + 272? (a) 1100 (b) 700 (c) 900
  30. 30.Best estimate of 51 × 23? (a) 1000 (b) 10000 (c) 100
  31. 31.Best estimate of 26 × 73? (a) 21000 (b) 2100 (c) 210
  32. 32.Best estimate of 576 + 677? (a) 1500 (b) 1300 (c) 1100
  33. 33.Best estimate of 159 + 647? (a) 800 (b) 600 (c) 1000
  34. 34.Best estimate of 585 + 373? (a) 1200 (b) 1000 (c) 800
  35. 35.Best estimate of 14 × 97? (a) 1000 (b) 100 (c) 10000
  36. 36.Best estimate of 451 + 171? (a) 500 (b) 700 (c) 900
  37. 37.Best estimate of 51 × 50? (a) 250 (b) 25000 (c) 2500
  38. 38.Best estimate of 93 × 81? (a) 720 (b) 72000 (c) 7200
  39. 39.Best estimate of 313 + 183? (a) 300 (b) 700 (c) 500
  40. 40.Best estimate of 67 × 86? (a) 630 (b) 63000 (c) 6300

Answer key

  1. 4000
  2. 1200
  3. 800
  4. 700
  5. 1300
  6. 1300
  7. 4500
  8. 1600
  9. 1100
  10. 900
  11. 500
  12. 900
  13. 1500
  14. 400
  15. 400
  16. 2400
  17. 1100
  18. 1200
  19. 1000
  20. 2000
  21. 1400
  22. 2800
  23. 1700
  24. 4000
  25. 3000
  26. 1200
  27. 1200
  28. 5000
  29. 900
  30. 1000
  31. 2100
  32. 1300
  33. 800
  34. 1000
  35. 1000
  36. 700
  37. 2500
  38. 7200
  39. 500
  40. 6300

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