This chapter reviews various tools from high school and college mathematics and is designed to be used more as a reference than as a tutorial. Mappings, also called functions, are basic to mathematics and programming. Like a function in a program, a mapping in math takes an argument of one type and maps it to an object of a particular type. Trigonometric functions are periodic and can take any angle as an argument. Density functions come up all the time in graphics and they can be surprisingly confusing at times, but getting a handle on what precisely they are will help us use them and navigate out of confusion when it strikes us. Density functions by themselves are useful for comparing relative concentrations at two different points. The cardinality of a set is the number of elements it contains.