Sum first and last digit of a number and make the product of remaining digits

Question

Guys, some person called me looking for some help. The question is: Make a program that make the sum of the first number and the last number, and the product of remaining numbers, for example:

Number: 1512
Sum: 1+2=3
Product=5*1=5

The only way I found was convert the number to an array. But that person wanted this solution without array, using only the number. It is possible ?

Answer 1

Solution for numbers of 4 digits
https://code.sololearn.com/cQFf11P2bQfS/#cpp

You can extend it to n digits by looping i*=10 until you hit n == n%i

Added for the n case, https://code.sololearn.com/c0G3kd3ZCw2R/#cpp

Special cases:
one digit: sum = digit and product = 0
two digits: sum = digit + digit and product = 0

Answer 2

Very good man. But I don't understood how to extend it.