[c] How to find the remainder of a division in C?

Which is the best way to find out whether the division of two numbers will return a remainder? Let us take for example, I have an array with values {3,5,7,8,9,17,19}. Now I need to find the perfect divisor of 51 from the above array. Is there any simpler way to solve this?

All the above answers are correct. Just providing with your dataset to find perfect divisor:

#include <stdio.h>

int main() 
{

int arr[7] = {3,5,7,8,9,17,19};
int j = 51;
int i = 0;

for (i=0 ; i < 7; i++) {
    if (j % arr[i] == 0)
        printf("%d is the perfect divisor of %d\n", arr[i], j);
}

return 0;
}

Use the modulus operator %, it returns the remainder.

int a = 5;
int b = 3;

if (a % b != 0) {
   printf("The remainder is: %i", a%b);
}