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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 289 · 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 631 + 290? (a) 900 (b) 700 (c) 1100
  2. 2.Best estimate of 28 × 68? (a) 21000 (b) 2100 (c) 210
  3. 3.Best estimate of 397 + 777? (a) 1000 (b) 1200 (c) 1400
  4. 4.Best estimate of 81 × 80? (a) 640 (b) 64000 (c) 6400
  5. 5.Best estimate of 26 × 98? (a) 300 (b) 3000 (c) 30000
  6. 6.Best estimate of 875 + 543? (a) 1200 (b) 1600 (c) 1400
  7. 7.Best estimate of 639 + 159? (a) 1000 (b) 600 (c) 800
  8. 8.Best estimate of 34 × 46? (a) 1500 (b) 150 (c) 15000
  9. 9.Best estimate of 36 × 94? (a) 360 (b) 3600 (c) 36000
  10. 10.Best estimate of 587 + 200? (a) 800 (b) 600 (c) 1000
  11. 11.Best estimate of 36 × 63? (a) 24000 (b) 240 (c) 2400
  12. 12.Best estimate of 22 × 82? (a) 160 (b) 16000 (c) 1600
  13. 13.Best estimate of 706 + 465? (a) 1000 (b) 1200 (c) 1400
  14. 14.Best estimate of 27 × 56? (a) 18000 (b) 180 (c) 1800
  15. 15.Best estimate of 231 + 624? (a) 1000 (b) 600 (c) 800
  16. 16.Best estimate of 13 × 37? (a) 40 (b) 400 (c) 4000
  17. 17.Best estimate of 199 + 262? (a) 300 (b) 500 (c) 700
  18. 18.Best estimate of 365 + 751? (a) 1400 (b) 1000 (c) 1200
  19. 19.Best estimate of 740 + 131? (a) 800 (b) 1000 (c) 600
  20. 20.Best estimate of 589 + 838? (a) 1600 (b) 1200 (c) 1400
  21. 21.Best estimate of 481 + 847? (a) 1100 (b) 1500 (c) 1300
  22. 22.Best estimate of 80 × 88? (a) 720 (b) 7200 (c) 72000
  23. 23.Best estimate of 707 + 854? (a) 1400 (b) 1600 (c) 1800
  24. 24.Best estimate of 771 + 856? (a) 1700 (b) 1500 (c) 1900
  25. 25.Best estimate of 131 + 554? (a) 900 (b) 700 (c) 500
  26. 26.Best estimate of 867 + 135? (a) 1200 (b) 1000 (c) 800
  27. 27.Best estimate of 125 + 459? (a) 600 (b) 800 (c) 400
  28. 28.Best estimate of 49 × 19? (a) 1000 (b) 10000 (c) 100
  29. 29.Best estimate of 815 + 313? (a) 1300 (b) 1100 (c) 900
  30. 30.Best estimate of 321 + 741? (a) 1000 (b) 1200 (c) 800
  31. 31.Best estimate of 680 + 201? (a) 1100 (b) 700 (c) 900
  32. 32.Best estimate of 38 × 27? (a) 1200 (b) 120 (c) 12000
  33. 33.Best estimate of 342 + 323? (a) 800 (b) 400 (c) 600
  34. 34.Best estimate of 777 + 695? (a) 1300 (b) 1500 (c) 1700
  35. 35.Best estimate of 14 × 66? (a) 700 (b) 70 (c) 7000
  36. 36.Best estimate of 93 × 37? (a) 3600 (b) 36000 (c) 360
  37. 37.Best estimate of 94 × 62? (a) 54000 (b) 540 (c) 5400
  38. 38.Best estimate of 167 + 475? (a) 700 (b) 500 (c) 900
  39. 39.Best estimate of 33 × 68? (a) 2100 (b) 210 (c) 21000
  40. 40.Best estimate of 87 × 16? (a) 1800 (b) 18000 (c) 180

Answer key

  1. 900
  2. 2100
  3. 1200
  4. 6400
  5. 3000
  6. 1400
  7. 800
  8. 1500
  9. 3600
  10. 800
  11. 2400
  12. 1600
  13. 1200
  14. 1800
  15. 800
  16. 400
  17. 500
  18. 1200
  19. 800
  20. 1400
  21. 1300
  22. 7200
  23. 1600
  24. 1700
  25. 700
  26. 1000
  27. 600
  28. 1000
  29. 1100
  30. 1000
  31. 900
  32. 1200
  33. 600
  34. 1500
  35. 700
  36. 3600
  37. 5400
  38. 700
  39. 2100
  40. 1800

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