 Most of the common mathematical functions belong to Java's math class, which is automatically imported into your Java programs. You don't need to import it. Here are the exponential methods. Log gives you the natural log, or log to the base E. The last item in this table isn't a method, it's a constant. Math.capitalE gives you an approximation to the mathematical constant E. Here are some of the trigonometric methods, plus the constant pi. These methods take their argument in radians, not in degrees. To refresh your memory, degrees go from 0 to 360 and tell you how far you've turned around. Radians tell how far you have walked along the circumference of the unit circle, a circle with radius 1, and radians go from 0 to 2 pi. People who aren't math majors expect to enter values in degrees and see results in degrees. That's why Java provides these methods for converting to radians and converting back to degrees. In addition to the cosine, sine, and tangent, Java also provides the inverse operations, the arc cosine, arc sine, and arc tangent methods. Here are methods for rounding. Ceiling rounds up to the nearest integer, floor rounds down to the nearest integer. Notice their behavior with negative numbers. R int rounds to the nearest integer. If a number is exactly between two integers, it rounds to the nearest even integer. Half the time it'll round up, half the time it'll round down, and it'll all average out. The round method returns along when you give it a double. That means you can't do this. Instead, you have to do a cast to make sure you get an integer. We have these methods to find the minimum and maximum of two numbers, and also an absolute value method. Finally, there's the random method, which gives you a random double from 0 up to but not including 1. Here's the generic formula for creating a random number in a given range. And here's how you might use it in a program to generate a random age between 18 up to but not including 66, which would be 18 through 65.