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How many of the natural numbers from 1 to 600, inclusive, contain the digit 5 at least once or the digit 6 at least once?

 Jan 5, 2021
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Use complementary counting and count the number of integers that don't contain 5 OR 6 and subtract it from the total numbers.

Ways to pick the first digit: 4. Possible ways: 1, 2, 3, 4

Second digit: 8 because you can't have 5 or 6

Third digit: 8 same as the second

4*8*8=256

Total numbers: 600

600-256=344

:D

 Jan 6, 2021

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