Example

A B C
7 4 =$A$1*B1
5 =$A$1*B2
6 =$A$1*B3
3 1 =$A$4*B4
4 =$A$4*B5

Isn't there a way to tell Excel to always multiply A*B, without using the
$A$? The reason I ask is we have hundreds of sections with new A values and
I don't want to put a new $$ formula in for each section. I was thinking of
something along the lines of A*B, if A=blank use last A value- but I can't
find any examples of this.