Question

This question is broken into 3 parts, each of which builds on the functions developed in the previous part. Note that you can (and should) still answer parts (b) and (c) even if you cannot answer the preceding parts - just assume that the functions work as they should, and continue.

Please explain the code as well

1. Write a C function called weighted_digit_sum that takes a single integer as input, and returns a weighted sum of that numbers digits. The last digit of the number (the ones digit) has a weight of 1, so should be added to the sum "as is". The second from last digit (the tens digit) has a weight of 2, and so should be multiplied by 2 then added to the sum. The third from last digit should be multiplied by 1 and added to the sum, and so on, with the weights alternating between 1 and 2 for each digit in turn. The final sum of all weighted digits should be returned from the function. For example, if the number 2561 was input to the function, the sum would be 1x1 + 2x6 + 1x5 + 2x2 = 22. HINT: Start from the right-most digit, and use simple C operators to find both the digit and the remaining number once that digit is removed.
2. Write another C function called reduced_sum which repeatedly calls the weighted_sum function developed in part (a) until the result is a single digit (less than 10). This value is then returned from the function. For example, if the same number 2561 was input to the function, it would return 4, since 2561 -> 22 -> 6 (1x2 + 2x2). Therefore 6 will be returned.
3. The only possible results of the reduced_sum function are 0 to 9. Write a main() program which uses the functions developed in parts (a) and (b) to find how many times each of these possible results occurs for the numbers from 0 to 10000. You should not print out the result of each test, just the total sum for each of the final results 0 through 9, so 10 total lines of output.

Answer 1

* C Program to Find Sum of First and Last Digit Of a Number */

#include <stdio.h>
#include <math.h>

int main()
{
   int Number, FirstDigit, Count, LastDigit, Sum = 0;

   printf("\n Please Enter any Number that you wish : ");
   scanf("%d", & Number);
  
   Count = log10(Number);   
   FirstDigit = Number / pow(10, Count);
  
   LastDigit = Number % 10;
  
   Sum = FirstDigit + LastDigit;
  
   printf(" \n The Sum of First Digit (%d) and Last Digit (%d) of %d = %d", FirstDigit, LastDigit, Number, Sum);

   return 0;
}