By default the loop variable is held in $_ but you can assign to a variable if you wish. It is not a good idea to alter loop variables inside the loop, that leads to all sorts of grief.

$ perl -Mstrict -Mwarnings -E '
> foreach my $outer ( 1 .. 3 )
> {
>     foreach my $inner ( 7 .. 9 )
>     {
>         say qq{$outer x $inner = @{ [ $outer * $inner ] }};
>     }
> }'
1 x 7 = 7
1 x 8 = 8
1 x 9 = 9
2 x 7 = 14
2 x 8 = 16
2 x 9 = 18
3 x 7 = 21
3 x 8 = 24
3 x 9 = 27
$
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I hope this is helpful.