Multiply by two elements of the matrix

The program would multiply by two elements of the following matrix: 4 7 8 6 9 1 5 0 3

No strip error, but stumbles when ruing

#include <stdio.h>
#include <stdio.h>
#include <conio.h>

int main(){ 
    int arr_num[3][3]={ {4,7,8},{6,9,1},{5,0,3}};
    int i=0,j=0;

    for (i=0;i<=2; i++)
         for (j=0;j<=2; i++)
              arr_num[i][j]=arr_num[i][j]*2;

              for (i=0;i<=2;i++)
              {
                  for (j=0;j<=2;j++)
                       printf("%d",arr_num[i][j]);
                       printf("n");
              }
              getch();
              retu 0;
}