If the numeric suggestions above don't solve your problem, read on...

Matching usually involves the m// operator, while substitution usually involves the s/// operator. While it is often useful and efficient to use the s/// operator in an if{} statement, when starting out you might go a little slower.

Assuming you have 2 variables, and you want to match the one (without leading zeros) to the other (with leading zeros), you might be looking for this:

$var1 = '020055';
$var2 = '20055';

if ( $var1 =~ /(0*)($var2)/ )
{
    print "Found match: <$1><$2>\n";
}
else
{
    print "No match: \$var1<$var1> \$var2<$var2>\n";
}
[download]

which yields:

Found match: <0><20055>
[download]

To be more helpful, we need to know more about your problem. For instance, are you reading each value from different files? Do the values have exactly 5 interesting digits?