# Rational Numbers in an Interval

Discrete Mathematics Level 3

How many rational numbers in the interval $$(0,1)$$, when expressed in lowest terms, have denominators less than or equal to 10 ?

Details and assumptions

Clarification: The numbers $$0$$ and $$1$$ are not included in the open interval $$(0,1)$$. On the other hand, the numbers $$0$$ and $$1$$ are included in the closed interval $$[0,1]$$.

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