# I exist sometimes

Given a list of integers $$1\cdots n$$, return the count of the number that have the number $$k$$ in them. For $$n\leq10^{9}$$ how many numbers have the number $$7$$ in them.

Details and Assumptions

For $$n\leq10$$, the number of occurrence of $$7$$ is one.

For $$n\leq100$$ the number of occurrence of $$7$$ is $$19$$...$$7,17,27,37,47,57,67,70,71\cdots ,79,87,97$$

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