This is the article you should read first, it and a bit of trigonometry and algebra will get you pretty far around here. The first article to read
The oldest series, being described in Euclid's Elements, has a wide range of applicability. Geometric Series
Exponents are a simple algebraic construction and notation; they are used in scientific notation and are implicit in the decimal notation. Roots are an intrinsic part of exponents (the fractional exponents). So, in this section the "original" exponent value (zero) is explored. Zero Exponent and Roots
The natural exponential is compared to other exponential bases, graphically. Natural exponent