If you want to print your data always in five columns:
1 2 3 4 5
11 322 32 45 6
10 20 30 40 50
20 21 12 13 14
6 7 .........
65 76 .........
60 70 .........
15 16 .........
Then you will need more loops!
You need an outer loop which works on groups of columns:
for (startCol = 0; startCol < dt.Columns.Count; startCol += 5)
{
...
}
Within that, you will need the pair of loops you already have, but with "j" starting from the startCol value instead of zero.