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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 525 · 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 311 + 134? (a) 400 (b) 200 (c) 600
  2. 2.Best estimate of 29 × 64? (a) 1800 (b) 180 (c) 18000
  3. 3.Best estimate of 92 × 86? (a) 8100 (b) 810 (c) 81000
  4. 4.Best estimate of 81 × 46? (a) 40000 (b) 4000 (c) 400
  5. 5.Best estimate of 91 × 79? (a) 7200 (b) 720 (c) 72000
  6. 6.Best estimate of 70 × 66? (a) 49000 (b) 4900 (c) 490
  7. 7.Best estimate of 96 × 86? (a) 9000 (b) 900 (c) 90000
  8. 8.Best estimate of 60 × 26? (a) 180 (b) 18000 (c) 1800
  9. 9.Best estimate of 747 + 202? (a) 700 (b) 1100 (c) 900
  10. 10.Best estimate of 16 × 56? (a) 12000 (b) 1200 (c) 120
  11. 11.Best estimate of 175 + 174? (a) 400 (b) 600 (c) 200
  12. 12.Best estimate of 149 + 510? (a) 400 (b) 600 (c) 800
  13. 13.Best estimate of 786 + 451? (a) 1500 (b) 1100 (c) 1300
  14. 14.Best estimate of 21 × 92? (a) 18000 (b) 1800 (c) 180
  15. 15.Best estimate of 434 + 830? (a) 1000 (b) 1200 (c) 1400
  16. 16.Best estimate of 23 × 19? (a) 40 (b) 4000 (c) 400
  17. 17.Best estimate of 661 + 374? (a) 1300 (b) 900 (c) 1100
  18. 18.Best estimate of 69 × 44? (a) 2800 (b) 28000 (c) 280
  19. 19.Best estimate of 223 + 391? (a) 400 (b) 800 (c) 600
  20. 20.Best estimate of 369 + 759? (a) 1200 (b) 1000 (c) 1400
  21. 21.Best estimate of 616 + 865? (a) 1500 (b) 1300 (c) 1700
  22. 22.Best estimate of 818 + 628? (a) 1600 (b) 1200 (c) 1400
  23. 23.Best estimate of 462 + 269? (a) 1000 (b) 600 (c) 800
  24. 24.Best estimate of 72 × 46? (a) 3500 (b) 35000 (c) 350
  25. 25.Best estimate of 366 + 195? (a) 400 (b) 600 (c) 800
  26. 26.Best estimate of 340 + 599? (a) 700 (b) 900 (c) 1100
  27. 27.Best estimate of 462 + 349? (a) 800 (b) 1000 (c) 600
  28. 28.Best estimate of 66 × 70? (a) 49000 (b) 4900 (c) 490
  29. 29.Best estimate of 94 × 36? (a) 36000 (b) 360 (c) 3600
  30. 30.Best estimate of 395 + 856? (a) 1300 (b) 1100 (c) 1500
  31. 31.Best estimate of 851 + 480? (a) 1600 (b) 1200 (c) 1400
  32. 32.Best estimate of 30 × 27? (a) 900 (b) 90 (c) 9000
  33. 33.Best estimate of 54 × 32? (a) 1500 (b) 15000 (c) 150
  34. 34.Best estimate of 354 + 830? (a) 1000 (b) 1200 (c) 1400
  35. 35.Best estimate of 268 + 607? (a) 1100 (b) 700 (c) 900
  36. 36.Best estimate of 649 + 424? (a) 1000 (b) 800 (c) 1200
  37. 37.Best estimate of 707 + 706? (a) 1400 (b) 1200 (c) 1600
  38. 38.Best estimate of 725 + 378? (a) 900 (b) 1300 (c) 1100
  39. 39.Best estimate of 68 × 12? (a) 700 (b) 7000 (c) 70
  40. 40.Best estimate of 829 + 695? (a) 1300 (b) 1500 (c) 1700

Answer key

  1. 400
  2. 1800
  3. 8100
  4. 4000
  5. 7200
  6. 4900
  7. 9000
  8. 1800
  9. 900
  10. 1200
  11. 400
  12. 600
  13. 1300
  14. 1800
  15. 1200
  16. 400
  17. 1100
  18. 2800
  19. 600
  20. 1200
  21. 1500
  22. 1400
  23. 800
  24. 3500
  25. 600
  26. 900
  27. 800
  28. 4900
  29. 3600
  30. 1300
  31. 1400
  32. 900
  33. 1500
  34. 1200
  35. 900
  36. 1000
  37. 1400
  38. 1100
  39. 700
  40. 1500

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