#! perl
use strict;
use warnings;
use bignum;

while (my $num = <DATA>)
{
    chomp $num;
    print 'float = ', $num, ', nearest int = ', int ($num + 0.5), "\n";
}

__DATA__
12345.6789
1_234_500_000_000_000_000_000_000.6789
10.49
11.5
12.500000001
1_234_500_000_000_000_000_000_042.499999
13