Actually, my second calculation is wrong.
Correct calculation is as follows:
9.6kW + 7.2kW = 16.8kW
16.8kW - 12kW = 4.8kW = 5kW (Note 1 says to round up, right?)
5% X 5kW = 25%
.25 X 8kW (from Row 1, Column C) = 2kW
8kW + 2kW = 10kW
10kW / 240V = 41.7kW
What's happening, is that I'm getting confused by the example on p.109 of the '02 NEC Handbook. It lists the three appliances' kW ratings: 8kW, 7kW, and 6kW. Because the equation uses 8kW and the highest individual appliance is also rated at 8kW, I incorrectly used the highest rated appliance (9.6kW) for my math. The Handbook example would make more sense if the highest rated appliance was 10kW.
