My father (born in 1934) went only to the primary school. From the age of 15, he ran a store with his older brother, that sold (among many other things) wool rug dyes to the villagers in Ağrı, a small town in the northeastern corner of Turkey. The dyes came in tin cans, and I remember reading the labels on them, which typically said the name of their manufacturer: Farbenfabriken, Bayer AG Leverkusen.

My father would carefully take a small scoop of dye and place in a rolled up white paper, and then weigh. The dyes were bought in very small quantities (5 gr, 10gr, 20gr etc), and weighed on a precise mechanical scale.

In the earlier days, my father was using pencil and paper to calculate the total cost of a purchase. Later he obtained a Facit mechanical calculator which was a technological wonder. He must have learned that very quickly, and has become very proficient. He would operate the machine very fast to calculate the final result, to the amazement of everyone watching him.

Those were my primary and middle school days, and I was spending some of my free time at the shop. I just learned addition and subtraction on this Facit machine by just watching him. Then he taught me that multiplication is just a series of additions and shifts; while division is a series of subtractions and shifts.

Later in my high school days, I discovered how to perform the restoring division and nonrestoring division algorithms on this calculator, by simply playing. These are not trivial algorithms at all!

Obviously I didn’t know at that time, but eventually I had become an algorithms researcher. My father was my first algorithms teacher.

Thank you my dear Father. Sana Allahın rahmetini diliyorum.