Scientists and engineers often work with very large or very small numbers, which are more easily expressed in exponential form or scientific symbols. A classic chemical example of numbers written in scientific symbols is the number of Avogadro (6.022 x 1023). Scientists usually use the speed of light (3.0x 108 m/s) to calculate. An example of a very small number is the charge of the electron (1.602x 10-19 coulombs). By moving decimal points to the left until only one number is left, a large number of numbers can be written in scientific notation. The moving number of decimal points gives an exponent, which is always positive for large numbers. For example, 3454000 = 3.454 x 106. For very small numbers, move the decimal point to the right until there is only one left decimal point. The number of right-moving gives a negative index: 0.0000005234 = 5.234 x 10-7. Not all calculators can handle scientific symbols, but you can easily perform scientific symbolic computation on a scientific calculator. To enter a number, look for the ^ button, which means “go up to power”, or Y X or X y, which means y goes up to power X or X goes up to y, respectively. Another common button is 10X, which makes scientific annotations easy. The way these button functions work depends on the brand of the calculator, so you need to read the instructions or test functions. You can either press 10x and enter the value of x, or enter the value of X and press the 10x button. Test this with a number you know to get the hang of it. Also remember that not all calculators follow the order of operations, where multiplication and division are performed before addition and subtraction. If your calculators have parentheses, it’s best to use them to ensure that calculations are performed correctly.