To express a number in exponential notation, write it in the form: c × 10n, where c is a number between 1 and 10 (e.g. 1, 2.5, 6.3, 9.8) and n is an integer (e.g. 1, -3, 6, -2). To find n, count the number of places that the decimal point must be moved to give the coefficient, c.