-dex is a suffix used by:
(1) André Joyce for the operand 510, a verbalized Roman numeral DX, as in the number name (arithmonym), googodex = g(2, 1020, 510). This was re-spelled with the silent -h- infix for "formerly high", to -dhex to distinguish it from the secondary meaning. googol
(2) -dex is also a suffix exclusive to ExE, designed by Sbiis Saibian. Let N be a number expressed in ExE as Ea@. In this case (N)-dex = Ea#N. With this, Sbiis Saibian forms several derivative googolisms.
Examples:
googol = E100 --> googoldex = E100#(E100) = E100#1#2
googolplex = E100#2 --> googolplexidex = E100#(E100#2) = E100#2#2
grangol = E100#100 --> grangoldex = E100#(E100#100) = E100#100#2
grangoldex = E100#100#2 --> grangoldudex = E100#(E100#100#2) = E100#100#3
eceton = E303 --> ecetondex = E303#(E303) = E303#1#2
grangolgong = E100,000#100,000 --> grangoldexigong = E100,000#(E100,000#100,000)
= E100,000#100,000#2