You don't look that old to me, Andrew.
I remember doing the same thing, spreading A3 ruled sheets glued together on the board room table and going thru each row and column with my adding machine. Luckily, we had just then graduated to "digital" desktop calculators from the old enter number/pull handle/print adding machines, so it wasn't too bad. For my sins, I had, once, as an articled clerk, had to add up pages of the phone book as I had nothing to do, so I learned to "touch type" on an adding machine.
The first PC I had (actually, the company had) was the IBM pictured in the article. It had 512k or RAM (upgraded from 256k because my boss would only buy the machine if it ran Flight Simulator - go figure). One floppy drive, on 10 mb hard disk, Lotus 123 included, and joy of joys, an epson WIDE CARRIAGE dot matrix printer. Once I discovered Sideways (gone, all are gone, the old familiar faces), there was no stopping my printouts, and no gluing either.
Those were the days....
Riaz