... manipulate the formatting of a number ... %.{$var}f does the trick.

Another way is the printf  * format specifier: 

c:\@Work\Perl\monks>perl -wMstrict -le
"my $p = 30;
 my $n = 1.111111111111111111111111111111;
 ;;
 printf '%0.*f', $p, $n;
"
1.111111111111111200000000000000

[download]
See sprintf for a discussion of all format specifiers.

Update: Actually,  %.{$var}f doesn't do any trick except to produce an "Invalid conversion in printf..." warning. But the syntax is correct in the OPed example code:
    printf( "%.${dig}f", $num );

Give a man a fish:  <%-{-{-{-<

In reply to Re: Why do I get random numbers? by AnomalousMonk
in thread Why do I get random numbers? by Cleggy

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