How many of the integers from 1 to 100, inclusive, have at least one digit equal to 6?
Solution
The integers between 1 and 100 that have a ones digit equal to 6 are , of which there are 10. The additional integers between 1 and 100 that have a tens digit equal to 6 are , of which there are 9. Since the digit 6 must occur as either the ones digit or the tens digit, there are integers between 1 and 100 with at least 1 digit equal to 6.
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