Hehe,,, normally i don't write Java code, but I am lazy this time :)

YOU ARE REALLY LAZY :
void MLT(int x)
{
    int r = 0;
    REP(i,3000)
    {
        int init = ((res[i]*x)+r);

        res[i] = init % 10;
        r = init / 10;
    }
}

I know. :)