need help with simple c program

Type your programming task here… need comments within the program to explain the code etc and whats going on.

An Albanian social security number has a sequence of digits

followed by a letter. This ‘check’ letter is determined from

the values of the digits and is used to ensure that the numbers

are correct. Write a program that, when given a ten-digit

number and letter as input, calculates a unique ‘check’

character corresponding to the given number according to the

following rules:

Add the five pairs of digits contained in the number

Take the remainder of dividing the result by 26

Select the letter in that position of the alphabet, starting

with ‘A’ in position 0, ‘B’ in position 1, and so on.

For example, if the input is 1122334455J, the program should

calculate (11 + 22 + 33 + 44 + 55) % 26 giving 9, and so ‘J’

is the ‘check’ character. This means that the social security

number quoted is correct. If the input was 1122334455M, your

program should detect that the check letter is incorrect,

and therefore that this social security number is false.