Like every contemporary boy, Beethoven went to start his primary school education around age of 5 or 6, (exact age is unknown). The school he attended was a secular state school in Bonn, called Tirocinium.
Like often the case with geniuses, he did not make any lasting impression at school and by the age of ten his father withdrew him from education in order to focus on his musical development.
Beethoven as an adult was well read and intelligent, but Mathematics was not his strong suit. In fact, all his life he was not able to fully understand and put into practice multiplication or how to divide. When he had to multiply something, he would write down the numbers as many times as he needed and then add them up.
Even during his last weeks on his deathbed he tried to learn the multiplication tables.
