**II. Function Keys**

F. Exponential and Logarithmic Keys1. (reciprocal) will take the reciprocal of the expression. You can also take the reciprocal of a value that has already been calculated by pressing after an expression has been calculated and then ENTER.

2. (squaring key) will square a number or expression.

3. (square root) will take the square root of a nonnegative number or expression. If the expression is negative you will get an error message like the one shown below in the screen on the right.

4. (Common log - base 10) takes the logarithm base 10 of any positive number. If you enter a negative expression or zero, an error message will be displayed as shown in the figure on the right below.

5. (10 raised to a power) is a key you can use to raise 10 to a power. Press and then the exponent.

6. (natural exponent) will raise the natural exponent e to any real power. If you want to just enter the value of e, press .

7. (natural logarithm) will calculate the natural log (log base e) of any nonnegative expression. If a negative value or a zero is entered you will get an error message like the one shown below on the right.