# of 3 of a kinds = 13 x 4 = 52.
Thirteen different denomations, two through ace.
Four suit pairings ... without the spade, heart, diamond and club - SHD, SHC, SDC and HDC.

# of remaining pairs, after the three of a kind = 12 x 6 = 78.
Twelve remaining denominations.
Six suit pairings ... SH, SD, SC, HD, HC, and DC.

Total # of full house variations is 52 x 78 = 4,056