aha, my lab's method comes out the same, but is a little less accurate for counting. I just count 1 of the larger squares, made up of 25 of the tiny squares (designated by #5 in the diagram you linked to).

Then divide that number by 4 X 10^-6 (corrects for volume in the cell), and multiply by your dilution factor. It gives the same answer if i use 1/5 (you counted 5 of those squares) of your count.