Complex Numbers
A   number  in  the form    a   +   bi, where   a   and b   are real    numbers,    is  called  a
complex number.
Contrapositive
“If p, then q,” is logically equivalent to “If not q, then not p.”
Average, Median, and Mode
Median  =   middle  value   (or average of  two middle  values) Mode    =   most
frequent    value Sum   of  the terms   =   (Average)   ×   (Number of  terms)
Percent Increase and Decrease
Average Rate Formula
Permutations and Combinations