Above, you can see the layout used for the practice differentials. Since neutrophils and lymphocytes will be the most common cells in most differentials, it is best to leave your hand on the bottom row of the keyboard when counting so that your index finger is on [V] and your pinky is on [Z]. For the other cells, try to move only one finger to press it so that you do not lose your place.

Until you get used to this layout, you will have to look up quite often to see which key to press. After a bit of practice, you will be able to do the differential without looking at the keys at all. It is important to note that different labs will likely use different layouts; this is just the layout my lab uses.

The counter will automatically stop at 100 counted cells. To recount or restart, simply press the reset button. The plus and minus buttons in each category allow for adjusting without resetting everything in case you accidentally press the wrong key.