Absolute value is symbolized by vertical lines surrounding the value, such as a .
This means that regardless of the sign of a, its absolute value is positive. The Greek capital sigma, S , is used to indicate a summation. Squaring, or taking k to the second power, is the most familiar example. If your calculator has an x y button, you can do the operation quickly. When you multiply two values that have different bases, you need to find each power separately, then multiply the results.