What Is a Flop?
A flop is one of the elementary arithmetic operations $latex +$, $latex -$, $latex *$, $latex /$ carried out on floating-point numbers. For example, evaluating the expression $latex (b - ax)/c$ takes three flops. A square root, which occurs infrequently in numerical computation, is also counted as one flop. As an example, the computation of…
Source: nhigham.com