If you are reading the inputs thru user by <STDIN> then you should
use chomp command to remove the newline charecter.
then you can see you are output.

chomp($firstNum=<STDIN>);
#$firstNum="7";
$secNum="5";
$product="35";
print " The product of the first number:$firstNum and second number:$s
+ecNum is:$product\n";
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thanks