#!/usr/bin/perl
use strict;
use warnings;
use feature 'say';
# Capture the number, and use a back-reference in the {} to define how many characters to match
my $myString = "1abc3cdfg\n";
$myString =~ s/(\d+)(??{ ".{$^N}" })//g;
say $myString;
IyEvdXNyL2Jpbi9wZXJsCnVzZSBzdHJpY3Q7CnVzZSB3YXJuaW5nczsKdXNlIGZlYXR1cmUgJ3NheSc7CiAKIyBDYXB0dXJlIHRoZSBudW1iZXIsIGFuZCB1c2UgYSBiYWNrLXJlZmVyZW5jZSBpbiB0aGUge30gdG8gZGVmaW5lIGhvdyBtYW55IGNoYXJhY3RlcnMgdG8gbWF0Y2gKbXkgJG15U3RyaW5nID0gIjFhYmMzY2RmZ1xuIjsgCiRteVN0cmluZyA9fiBzLyhcZCspKD8/eyAiLnskXk59IiB9KS8vZzsKc2F5ICRteVN0cmluZzs=