#!/usr/bin/env perl

use strict;
use warnings;
use JSON::PP;

my $data = {
        'book' => {
            'title' => JSON::PP::true,
            'pages' => 5.03 #this number
        }
    };

my $json = encode_json($data);
print $json, "\n";

__END__
{"book":{"pages":5.03,"title":true}}

##</code><code>##

my $data = {
    book => {
        title => JSON::PP::true,
        pages => 0+$number,
    }
};