What is the meaning of this number displayed in my R environment?

Question

My question is really silly, I want to know what the meaning of this number displayed in my R environment, is it $2.2\times e^{-16}$?

Answer 1

2.2e-16 means $ 2.2 \times 10^{-16}$. It is a shorthand convention for scientific notation hanging over, I think, originally from Fortran programming language.