For n=9,

0 1 2
3 4 5
6 7 8

For n=6,

Either,
0 1 2
3 4 5
or
0 1
2 3
4 5

int rowlen = (sqrt(n))
int collen = (n/rowlen)
int no = 0;

for (int i = 0; i < rowlen-1) {
    for (int j = 0; j < collen-1) {

        System.out.print(no+"t")
        no++;

    }

    System.out.println()
}

var n = 10;

var cols = 0;

for(var i=0; i<n; i++) {
    if(i>1 && ((cols === 0 && n%i === 0) || (cols>0 && i%cols===0))) {
        if(cols===0) { // we've found our first prime factor;
                       // this value will be used as the number of columns
            cols = i;
        }
        print("n");
    }
    print(i);
}