# How to use WikiCalculators?

#### 1. In order to calculate the value of an equation, you only need to enter values for the parameters shown in the right-hand side of the equation and then click "Calculate".

For example, how to calculate the total surface area of a cone? Given the radius r and slant height l of a cone, the formula for total surface area S is as follows. The calculator specific for this purpose is You enter values for r and l, then click the "Calculate" button, the total surface area will show in the box on the right of S.

#### 2. Units

If a parameter has a unit, the unit drop-box will show on the right side of the parameter. By default, the international standard unit will be selected. For example, for a length parameter, "meter" will be used as the default unit. If you don't change any unit, the calculator will work as a dimenionless calculator.

After you enter a value for a parameter that has a unit, the value will be bound to the unit shown on the right side automatically. If you change a unit, the value will be converted to new unit automatically.

If you want to use a unit other than the default one for a parameter, you should select the unit first, then enter the value. For example, in the above calculator for the total surface area of a cone, the radius r is 3.6 inch, you should select "inch" from the drop-down unit box, then enter the value 3.6. Then if you change unit to 'foot', a unit conversion (from 'inch' to 'foot') will be done automatically and the value of r will be updated to 0.3.

#### 3. How to enter numbers?

The wiki-calculators are very flexiable and can take numbers in many formats. We still use the above calculator for the total surface area of a cone as example,for the radius r
• if r = 3.6, just type 3.6
• if r = 4.7 × 106,enter 4.7e6, 4.7e+6 or 4.7E6
• if r = 4.7 × 10-7, enter 4.7e-7 or 4.7E-7
• if r = 1/3, just enter 1/3

#### 4. Precision

You can format calculation results to a certain precision by selecting a value for "Precision" in the calculator. You can choose Precision from 0 to 9.
• For a number that is greater than 1 or less than -1, i.e. x > 1.0 or x < -1.0, the Precision is the precision after the decimal point. It doesn't matter how large the number is before the decimal point. If Precision=n, results will be formatted with n numbers of digits after the decimal point.
```For example, for num = 930.9805,
If Precision=0, result = 931
If Precision=1, result = 931.0
If Precision=2, result = 930.98
If Precision=3, result = 930.981

```
• For a number x that is less than 1 but greater than -1, i.e. -1.0 < x < 1.0, if Precision=n, the total number of digits of a result will be formatted to the specified length n. It means that you're setting the overall precision. Here, it matters how large the number is before and after the decimal point.
```For example, for num =0.09309805,
If Precision=0, result = 0.09
If Precision=1, result = 0.09
If Precision=2, result = 0.093
If Precision=3, result = 0.0931
```

Last Updated: 23 August, 2012