# First make the program know the two numbers:
$Number1 = 48;
$Number2 = 12;

# Now divide the numbers:
$Result = $Number1 / $Number2;

# ...and look if we got a decimal:

##</code><code>##

# Using your sub
is_integer_string($Result)

# Look for a .
$Result =~ /\./;

# Check if the number is the same as its integer part:
$Result == int($Result)

##</code><code>##

if (condition) { print "Yes"; } else { print "No"; }

##</code><code>##

sub is_integer_string {
 my $N = $_[0] + 0;
 return $N =~ /^\-?\d+$/;
}