Lo-Pee-Tal

It’s 1696 France. Your walking down a cobbled stone path. A man greets you, you make small chat. You find out he’s headed to the congregation of oratory.. where he speaks.. then to his tutor jacob Bernoulli, with whom he meets, then to work on a theory of limits – which posterity will call by his last name. The man is Guillaume Francois Atoine de L'Hospital, "a man of the highest social distinction whose love of learning drove him to devote much of his short life to scientific writing"

Fast forward 323 Earth Sun orbit rotations – it's 2010. I’m sitting in a library with a book , whose text is using this man’s very theory to solve problems. Your trying to find a value for some relation but the normal method gives an irrational fraction. The man’s secret was a pattern – if the 0/0 fraction exists, take numerator and denominator’s derivatives, plug in the value your looking for – bam, you have it.

In notation

The guy - the jacob one - is the one in the pic.
who cares who did it.. neat trick nonetheless