Newton was interested in the mathematics of motion.
He discovered the branch of mathematics (fluxions) in which an
unknown number keeps changing. The word fluxion came from the word
flux, which means "constant changing or flowing." Today, it
is called calculus and taught in high school and college. Using
fluxions, Newton learned how to find the area under a curve called
Here is an example of a formula for finding
the integral ( area under a curve).
i = 1
f(xi)(xi - xi -