1/? the (abridged) story of Curt Herzstark, the brilliant Viennese engineer who invented an incredibly complex handheld mechanical calculator in the Buchenwald concentration camp

"I had an idea… I should look at everything backwards… I'll pretend I have already invented everything. What does this kind of machine have to look like, so someone could use it?” Curta calculator: The mechanical marvel born in a Nazi death camp: