Question 338582
You're on the right track.
It would be {{{9^7}}} rows.
Think of it like writing a {{{7}}} digit number
{{{ABCDEFG}}}
And the values of {{{A-G}}} can vary from {{{1-9}}}. 
So then you would have 
{{{9*9*9*9*9*9*9}}} possible choices for each combination.
or {{{9^7}}}.