my $string = '100,two hundred,300,400,500,600,700,800';
my @checks = ( qw/200 400 600 700 900/ );

my @items = split(/,/, $string);

for my $check (@checks) {
    if ( grep { $_ eq $checks } @items ) {
        print "'${check}' is in '${string}'\n";
    }
    else {
        print "'${check}' is NOT in '${string}'\n";
    }
}