Muchas gracias, pero me sigue dando error
   Cita:  #include <stdio.h>
 
int fn(int num)
{
    int percent = (num * 100);
    return percent;
}
 
int main()
{
    int num;
    scanf("%d",num);
    int b = fn();
    printf("%d",b);
}
    Me dice: 
 Cita:  In function 'main';
error: too few arguments to function 'fn' (line 13)
Build finished: 1 errors, 0 warnings