change.pl

use strict;
use warnings;
 
print "Amount (in pounds)?\n";
chomp(my $amount = <>);
$amount = sprintf('%.1f', $amount * 100);

my %coinage = (
	1   => 'pennies',
	2   => 'tuppennies',
	5   => 'five pence pieces',
	10  => 'ten pence pieces',
	20  => 'twenty pence pieces',
	50  => 'fifty pence pieces',
	100 => 'pound coins',
	200 => 'two pound coins',
);

my $remainder = $amount;
for my $value (sort { $b <=> $a } keys %coinage) {
	my $quantity = int($remainder / $value);
	print "$quantity $coinage{$value}\n" if $quantity;
	$remainder %= $value;
}