Here is your example code with a few changes, I'm really pushed for time, this is by no means perfect, just something to help you get started:

#!/usr/bin/perl
use strict;
use warnings;

print"###simple calculator program##\n\n";

my $opt2="";

while ($opt2 ne 'y'){
    
    my $ans;
    print "enter the first number\n";
    chomp( my $num1 = <> );
    
    print "enter the second number\n";
    chomp( my $num2 = <> );
    
    print "enter your option\n\+ for addition\n\- for subtraction\n\* 
+for multiplication\n\/ for divison\n option:";
    
    chomp(my $opt = <>);
    if ($opt eq '+'){
        print "you pressed the \+key\n";
        $ans = $num1 + $num2;
        print "the answer is $ans\n";
    }elsif ($opt eq '-'){
        print "you pressed the \-key\n";
        $ans = $num1 - $num2;
        print "the answer is $ans\n";
    }elsif ($opt eq '*'){
        print "you pressed the \*key\n";
        $ans = $num1 * $num2;
        print "the answer is $ans\n";
    }elsif ($opt eq '/'){
        print "you pressed the \/key\n";
        $ans = $num1 / $num2;
        print "the answer is $ans\n";
    }else{
        print "you have entered wrong option\n";
        print "do you want to continue press y or n?\n";
        chomp ($opt2 =<>);
    }
}
[download]

Firstly fix your indentation, making things easier to read can help you find out what's wrong. I removed the press any key to contiune type thing, it felt pointless.

You have lots ot elsifs but two elses for the same if condition, this is going to cause problems.

• Consider a saner option to exit the program.
• Consider how to deal with uppercase input.
• Consider how to deal with user input which isn't what you expect? e.g. **x,red...
• perlintro
• http://learn.perl.org
• http://perldoc.perl.org
• Consider using more meaningful variable names
• The tutorials section of this site, Use strict warnings and diagnostics or die, Debugging and Optimization
• How do I post a question effectively?

---

---

Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Titles consisting of a single word are discouraged, and in most cases are disallowed outright.

Read Where should I post X? if you're not absolutely sure you're posting in the right place.

Please read these before you post! —

• How do I compose an effective node title?
• How do I post a question effectively?
• Markup in the Monastery

Posts may use any of the Perl Monks Approved HTML tags:

a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr

You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)

	For:		Use:
	&		&
	<		&lt;
	>		&gt;
	[		&#91;
	]		&#93;

Link using PerlMonks shortcuts! What shortcuts can I use for linking?

See Writeup Formatting Tips and other pages linked from there for more info.