# I exist sometimes

**Computer Science**Level 3

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 \(19\)...\(7,17,27,37,47,57,67,70,71\cdots ,79,87,97\)