SOLUTION: How many positive two-digit integers are multiple of 3?

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Question 695854: How many positive two-digit integers are multiple of 3?
Answer by KMST(5328) About Me  (Show Source):
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All multiples of 3 can be expressed as 3n , where n is a positive integer.
A two digit number is at least 10 (greater than 9),
and no more than 99 (lesser than or equal to 99).
We can write that as the compound inequality
9%3C3n%3C=99

9%3C3n%3C=99 --> 9%2F3%3C3n%2F3%3C=99%2F3 --> 3%3Cn%3C=33
So n could be any of the first 33 positives integers,
except of the first 3.
That gives us 33-3=highlight%2830%29 choices for n,
meaning there are highlight%2830%29 positive integers that are
multiples of 3 and two-digit positive integers.