Divide the slope expressed as a percentage by 100 to convert to a standard slope. For example, if your slope expressed as a percent equals 70 percent, divide 70 by 100 to get 0.7.
Enter the result on the calculator. In this example, enter "0.7."
Calculate the arctangent of the slope by pushing the "tan^-1" or "arctan" to find the measure of the angle. In this example, the arctangent of 0.7 equals 50.70 degrees.