# Mike's Toolbox

## Using Mike's Toolbox Scientific Calculator

Mike's Toolbox Scientific Calculator is similar to actual calculators you might buy in the store. It has a numeric keypad for entering numbers, and the other buttons operate on the numbers that have been entered. This page will show you what each button does so that you can use the calculator most effectively.

Here is a full working calculator with the different sections highlighted in different colors. Use the colors to find the explanations below.

### Numeric Entry

 ... Numbers: these buttons are used to enter numbers into the calculator Decimal Point: inserts a decimal point at the end of the number being entered Change Sign: changes the sign of a number from positive to negative or vice versa — has no effect if the number displayed is equal to zero Clear: clears the display and cancels any pending operation such as if you were in the middle of calculating the sum of two numbers; has no effect on the memory functions (see below) Clear Entry: clears the display but remembers any current calculation being performed — use this button if you make a mistake entering a number and want to re-enter it Delete: erases the last digit of the displayed number Help: displays this help page

### Arithmetic Functions

 Addition: enter a number, press +, then enter a second number and press = to calculate the sum of the two numbers Subtraction: enter a number, press −, then enter a second number and press = to calculate the difference between the two numbers Multiplication: enter a number, press ×, then enter a second number and press = to calculate the product of the two numbers Division: enter a number, press ÷, then enter a second number and press = to calculate the first number divided by the second Calculate: performs the current calculation as described above

### Basic Operations

Square: computes the square of the displayed number; for example if the display shows the number 4, the calculator will replace that with 16, which is 4 × 4
Cube: computes the cube of the displayed number; for example if the display shows the number 4, the calculator will replace that with 64, which is 4 × 4 × 4
Exponentiation: enter a number y, then press the yx button followed by the number x and press = to compute y to the x power
Square Root: computes the square root of the displayed number; for example if the display shows the number 16, the calculator will replace that by the number 4 since 4 × 4 is 16. This is the opposite of the x2 button.
Cube Root: computes the cube root of the displayed number; for example if the display shows the number 8, the calculator will replace that by the number 2 since 2 × 2 × 2 is 8. This is the opposite of the x3 button.
Factorial: computes the factorial of the displayed number; for example if the display shows the number 4, the calculator will replace that by the number 24 since 4! = 4 × 3 × 2 × 1 which is 24
Swap: swaps the stored number with the displayed number prior to performing a calculation; for example if you first enter the exponent x, then press the yx button followed by the number y, you can fix your mistake by pressing x↔y prior to pressing the = button.
Inverse: calculates the reciprocal of the displayed number, which is 1 divided by the number; if you multiply a number by its inverse, the result is 1
Round: rounds the displayed number to the nearest whole number
Percentage: if no operation is pending, then the displayed number is divided by 100; otherwise what happens depends on the current calculation as follows:
 Percentage Addition: to calculate a 20 percent increase of the number 5, for example, first enter the number 5, then press + followed by the number 20 and the % button; at that point the calculator will replace the displayed value of 20 with 20 percent of 5, which is 1 — the calculator remembers the number 5 and the fact that addition is being performed, so when you finally press the = button, it adds 5 + 1 and displays the result of 6 Percentage Subtraction: to calculate a 25 percent decrease of the number 8, for example, first enter the number 8, then press − followed by the number 25 and the % button; at that point the calculator will replace the displayed value of 25 with 25 percent of 8, which is 2 — the calculator remembers the number 8 and the fact that subtraction is being performed, so when you finally press the = button, it subtracts 8 − 2 and displays the result of 6 Percentage Multiplication: calculates simple percentages; to find 15 percent of your \$60 restaurant tab, enter 60 followed by × then 15 and the % button — the result of \$9 is displayed Percentage Division: this is an odd one; if you want to know how many years it will take to double your money if it earns, say, 6 percent per year, then you would enter 2, since that is the multiple of your investment, then the ÷ button followed by 6 and the % button

### Memory

If you calculate an important result and want the calculator to remember it for use later, you will want to use the memory functions shown here:

 Memory Store: stores the displayed number in the calculator's memory, erasing any previously stored number Memory Plus: adds the displayed number to the number in the calculator's memory and stores the result in the memory; also increases an internal counter used by the AVG button Memory Minus: subtracts the displayed number from the number in the calculator's memory and stores the result in the memory; also increases an internal counter used by the AVG button Memory Recall: displays the number currently stored in the calculator's memory Memory Clear: stores the number zero in the calculator's memory and resets the counter used by the AVG button to zero as well Average: computes the average of all the numbers added to the memory using the M+ and M− buttons

### Trigonometric Functions

 Pi: displays the famous constant representing the ratio of the circumference of a circle to its diameter; approximately 3.1415926 Sine: computes the sine of the displayed number expressed in radians Arcsine: computes the number of radians of the arc whose sine is the displayed number (which must be between −1 and 1) Cosine: computes the cosine of the displayed number expressed in radians Arccosine: computes the number of radians of the arc whose cosine is the displayed number (which must be between −1 and 1) Tangent: computes the tangent of the displayed number expressed in radians Arctangent: computes the number of radians of the arc whose tangent is the displayed number

### Logarithms

 Euler's Number: displays the value of the important constant which is the base of the natural logarithm; approximately 2.71828 Base-10 Logarithm: computes the exponent of the number 10 required to calculate the displayed number Base-2 Logarithm: computes the exponent of the number 2 required to calculate the displayed number Natural Logarithm: computes the exponent of the number e required to calculate the displayed number Exponentiation Base-10: computes the power of 10 where 10 is raised to the displayed number; for example, if 2 is displayed, it will be replaced by 100 which is 102 Exponentiation Base-2: computes the power of 2 where 2 is raised to the displayed number; for example, if 5 is displayed, it will be replaced by 32 which is 25 Exponentiation Base-e: computes the power of e where e is raised to the displayed number