All numbers in AMX-X are stored in a 4-byte cell. Each byte can hold a value between 0 and 255. So you can pack 4 0 to 255 values within 1 cell. If the values are between 1 and 6 only, you can pack more than just 4 into a cell.
For your example, you need 6 so this idea wouldn't work.
I would use nVault Array, it's the simplest if you are not experienced.