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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 682 · 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 190 + 719? (a) 700 (b) 1100 (c) 900
  2. 2.Best estimate of 671 + 337? (a) 1200 (b) 1000 (c) 800
  3. 3.Best estimate of 63 × 16? (a) 12000 (b) 120 (c) 1200
  4. 4.Best estimate of 669 + 334? (a) 800 (b) 1000 (c) 1200
  5. 5.Best estimate of 861 + 254? (a) 1200 (b) 1000 (c) 1400
  6. 6.Best estimate of 451 + 142? (a) 400 (b) 800 (c) 600
  7. 7.Best estimate of 39 × 76? (a) 32000 (b) 320 (c) 3200
  8. 8.Best estimate of 23 × 18? (a) 4000 (b) 40 (c) 400
  9. 9.Best estimate of 19 × 56? (a) 12000 (b) 120 (c) 1200
  10. 10.Best estimate of 254 + 455? (a) 800 (b) 1000 (c) 600
  11. 11.Best estimate of 47 × 96? (a) 50000 (b) 5000 (c) 500
  12. 12.Best estimate of 797 + 287? (a) 1100 (b) 1300 (c) 900
  13. 13.Best estimate of 535 + 753? (a) 1300 (b) 1100 (c) 1500
  14. 14.Best estimate of 20 × 43? (a) 800 (b) 80 (c) 8000
  15. 15.Best estimate of 635 + 180? (a) 600 (b) 800 (c) 1000
  16. 16.Best estimate of 745 + 453? (a) 1400 (b) 1200 (c) 1000
  17. 17.Best estimate of 290 + 842? (a) 1100 (b) 1300 (c) 900
  18. 18.Best estimate of 367 + 651? (a) 1300 (b) 1100 (c) 900
  19. 19.Best estimate of 402 + 215? (a) 800 (b) 400 (c) 600
  20. 20.Best estimate of 86 × 83? (a) 720 (b) 7200 (c) 72000
  21. 21.Best estimate of 76 × 26? (a) 24000 (b) 2400 (c) 240
  22. 22.Best estimate of 789 + 198? (a) 1000 (b) 800 (c) 1200
  23. 23.Best estimate of 142 + 274? (a) 600 (b) 200 (c) 400
  24. 24.Best estimate of 80 × 56? (a) 480 (b) 48000 (c) 4800
  25. 25.Best estimate of 64 × 79? (a) 48000 (b) 480 (c) 4800
  26. 26.Best estimate of 40 × 17? (a) 80 (b) 8000 (c) 800
  27. 27.Best estimate of 378 + 257? (a) 700 (b) 500 (c) 900
  28. 28.Best estimate of 49 × 28? (a) 150 (b) 15000 (c) 1500
  29. 29.Best estimate of 56 × 36? (a) 2400 (b) 24000 (c) 240
  30. 30.Best estimate of 46 × 46? (a) 2500 (b) 250 (c) 25000
  31. 31.Best estimate of 21 × 12? (a) 200 (b) 20 (c) 2000
  32. 32.Best estimate of 78 × 88? (a) 72000 (b) 7200 (c) 720
  33. 33.Best estimate of 727 + 328? (a) 800 (b) 1000 (c) 1200
  34. 34.Best estimate of 424 + 229? (a) 800 (b) 400 (c) 600
  35. 35.Best estimate of 489 + 616? (a) 900 (b) 1300 (c) 1100
  36. 36.Best estimate of 287 + 691? (a) 800 (b) 1000 (c) 1200
  37. 37.Best estimate of 262 + 348? (a) 600 (b) 800 (c) 400
  38. 38.Best estimate of 31 × 14? (a) 30 (b) 300 (c) 3000
  39. 39.Best estimate of 181 + 820? (a) 800 (b) 1200 (c) 1000
  40. 40.Best estimate of 305 + 567? (a) 700 (b) 1100 (c) 900

Answer key

  1. 900
  2. 1000
  3. 1200
  4. 1000
  5. 1200
  6. 600
  7. 3200
  8. 400
  9. 1200
  10. 800
  11. 5000
  12. 1100
  13. 1300
  14. 800
  15. 800
  16. 1200
  17. 1100
  18. 1100
  19. 600
  20. 7200
  21. 2400
  22. 1000
  23. 400
  24. 4800
  25. 4800
  26. 800
  27. 700
  28. 1500
  29. 2400
  30. 2500
  31. 200
  32. 7200
  33. 1000
  34. 600
  35. 1100
  36. 1000
  37. 600
  38. 300
  39. 1000
  40. 900

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