In the c++ programming language, a variable name must start with a letter or the underscore character ( and succeeding characters must be letters, digits, or the underscore character. uppercase and lowercase letters are considered to be different characters.
(a) how many variable names with exactly five characters can be formed in c++? (b) how many are there with at most five characters? (c) how many are there with at most five characters, if they must read exactly the same forwards and backwards? for example, kayak and t55t are admissible, but kayak is not.