When I began work as an articled clerk in an insurance company in 1960, everything was done by hand and in the head. Only sometime later did the first hand-operated adding machine arrive which relieved the head but not the hand (or arm). Left-handers would have given their right arm to be right-handers because they were the only people those machines were designed for.
Later, much later, in fact, as late as 1970 when I had already emigrated to Australia and started work in a chartered accountant's office in New Guinea, did those hurdy-gurdy calculators arrive. What progress! No more page-long hand-written divisions or multiplications; those machines would do it all at the speed of a limp wrist! There were Odhners and Facits and Brunsvigas and they stayed around for decades.
While not-so-pocket-sized silent and electricity- and later battery-operated calculators gradually replaced the clanky hurdy-gurdies - even though hand-operated adding-machines still kept us going through the not infrequent New Guinea power black-outs - those muscle- although not mind-building hand-operated machines left their unintended mark on a whole generation of accountants of that time - see photo below.
It's only now in old age, after everything has begun to shrivel anyway, that we are regaining a slightly balanced look. Too late to claim compo!