Example:

    1101
x    101
--------
    1101
   0000x
+ 1101xx
--------
 1000001

int k;
int factor = 0;
long b1, b2;
int i = 0;
int[] sum = new int[20];

while (b2 != 0) {
k = b2 % 10;
sum[i] = b1 * k * factor;
i++;
b2 = b2 / 10;
factor = factor * 10;
}