Sushiguy,
Just to be clear, for HiLo the divisor is ALWAYS the whole decks unseen. When The G Man says "quarter deck", that means you express the undealt decks using quarter-deck accuracy, but you still divide by whole decks: it's just a fraction.
For example, if 65 cards (so one-and-a-quarter decks) are unseen and the RC is +2, the TC is +2/1.25 = +1.6, which is usually truncated to give a TC of +1.
If you instead divided by quarter-decks, then you have 5 quarter-decks unseen, so you would say the TC is +2/5 = +0.4. See the difference?
Hope this helps!
Dog Hand