There were a number of things that were unique about the villain's crime campaign. First of all, he only stole items when they were at their most valuable. (I explained this concept to editor Julie Schwartz this way: Five minutes before the opening of a Broadway show, the Calculator steals all the costumes. If he stole them the day before, they could be replaced.)
Second, he had a secret calculation that he punched in when he was captured by the hero. This prevented that hero from ever capturing him again.
Finally, he appeared in a series of back-up stories in Detective Comics, battling and being defeated by The Atom, Black Canary, Elongated Man, Green Arrow, and Hawkman, before facing off with Batman in an issue-long conclusion to the series. Before this final battle, The Calculator had punched in his secret code and none of the heroes was able to capture him a second time. Batman, however, maneuvered him into a situation in which The Calculator actually captured himself.
I brought The Calculator back five years later in a team-up story in Action Comics featuring The Atom and Air Wave. The Atom, because of his prior encounter with the villain, was unable to defeat him, so he called on Air Wave to do so.
And I brought him back one more time in my Hero Hotline miniseries in 1989, this time hinting that he had some longtime connection to The Coordinator, who ran HH.
The character was reinvented by other writers after that. He was changed from a costumed villain into a techie who used the internet to aid other criminals in their nefarious deeds. This version played a major role in a couple of the company-wide crossovers.
In the Batman: The Brave & the Bold cartoon series episode "Night of the Huntress," there is another incarnation that is a cross between the two. This Calculator, an overweight guy named Myron who lives in his mother's basement, wears the top half of the costume but sits at a computer providing info for other criminals.
Tonight's Calculator is being played by Tom Amandes. I expect he will be much closer to the latter-day version, but it will still be fun to see a character I created forty years ago making it to the live-action DC Universe.