Scientists and engineers often work with very large or very small numbers, which are more easily expressed in exponential form or scientific notation. A classic chemistry example of a number written in scientific notation is Avogadro's number (6.022 x 1023). Scientists commonly perform calculations using the speed of light (3.0 x 108 m/s). An example of a very small number is the electrical charge of an electron (1.602 x 10-19Coulombs).