You've learned how to talk to the user, now its time to learn how to listen, but first you must know about variables. Variables are such a simple component of any programming language, the concept should be easy to grasp, even without a complete explanation. Then, further in the program, when X is mentioned, the computer will think of the value 10, instead of the letter 'X'. Of course, the value of X can easily be changed further down in the code. The name of the actual variable must consist only of 'a' to 'z', 'A' to 'Z', the underscore or numbers.
Names are case-sensitive, so 'a' is completely different from 'A'.
OK, before assigning a value to a variable, it must be created, and its data-type defined. The data-type of a variable decides what sort of data the variable can store. There are four important ones, characters, integers, long integers, and floating point decimal numbers . In C, there names are char, int, long, and float respectively. An integer is a whole number like '2', of '175', but not '2.1'.