Рекурсия: вычисление суммы и количества цифр числа, максимальной и минимальной его цифры

#include <stdio.h>
#include <stdio.h>
#include <math.h>
 
unsigned int sum(unsigned int number) { return ( number > 9 ) ? number % 10 + sum(number / 10) : number; }
 
unsigned int cnt(unsigned int number) { return ( number > 9 ) ? 1 + cnt(number / 10) : 1; }
 
unsigned int max(unsigned int number) {
    unsigned int first, last, div;
    
    if ( number < 10 )
        return number;
 
    div = (unsigned int)pow(10.0, floor(log10((double)number)));
    first = number / div;
    last = number % 10;
    
    return ( first > last ) ? max(number / 10) : max(number - first * div);
}
 
unsigned int min(unsigned int number){
    unsigned int first, last, div;
    
    if ( number < 10 )
        return number;
 
    div = (unsigned int)pow(10.0, floor(log10((double)number)));
    first = number / div;
    last = number % 10;
    
    return ( first < last ) ? min(number / 10) : min(number - first * div);
}
 
int main(void){
    unsigned int number;
    
    while ( printf("Number: ") && scanf("%u", &number) == 1 && number )
        printf("\tSum:\t%u\n\tCount:\t%u\n\tMax:\t%u\n\tMin:\t%u\n", sum(number), cnt(number), max(number), min(number));
    
    return 0;
}

#include <stdio.h>
#include <math.h>
 
unsigned int sum(unsigned int number) { return ( number > 9 ) ? number % 10 + sum(number / 10) : number; }
 
unsigned int cnt(unsigned int number) { return (unsigned int)log10((double)number) + 1; }
 
unsigned int max(unsigned int number) { 
    return ( number < 10 ) ? number : ( number % 10 > number % 100 / 10 ) ?
        max((number / 100) * 10 + number % 10) : max(number / 10);
}
 
unsigned int min(unsigned int number){
    return ( number < 10 ) ? number : (number % 10 < number % 100 / 10 ) ?
        min((number / 100) * 10 + number % 10) : min(number / 10);
}
 
int main(void){
    unsigned int number;
    
    while ( printf("Number: ") && scanf("%u", &number) == 1 && number )
        printf("\tSum:\t%u\n\tCount:\t%u\n\tMax:\t%u\n\tMin:\t%u\n", sum(number), cnt(number), max(number), min(number));
    
    return 0;
}