simple program help required

The circumfrence of a circle is
#!/usr/bin/perl
print 2 * 3.141592654 * 12.50 \n"; # pi= 3.141592654
# r= 12.50

I need a simple program showing me all the steps..to modify the above to prompt for and accept a radius from the person running the program. So if the person enters 12.5 for the radius,we get the circumference . # 78.5
thanks
Q2

Hello,
what have you done so far? we would like to see.
which language do you want the program to be in C/C++/bash/perl/php/java/javascript/ruby?
please specify

P.S. How much can you pay if we do it for you for free.?
Regards.

Perl 5.10

ps : if pay = free

Hello ,
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