# Forming Divisible Numbers

Probability Level 4

Seven digits from the numbers 1, 2, 3, 4, 5, 6, 7, 8, and 9 are written in random order. Find the probability that this seven-digit number is divisible by 9.

If the answer is in the form $\frac{a}{b}$ for coprime positive integers, submit as $a + b$.