# Difference between revisions of "Grade calculations"

A grade calculation is a formula used to determine grades, based (optionally) on other grade items. Note that this is not the same as Calculated question types.

## Setting a grade calculation

Calculator symbol
To set a grade calculation:
1. Login as teacher or other user with permission to edit grades.
2. Click on Grades in the course administration block.
3. Click the 'Categories and items' tab (or select it from the gradebook dropdown menu).
4. Click the 'calculator symbol' (in the 'Actions' column) opposite the grade category you wish to set a calculation for.
5. Add the calculation then click the 'Save changes' button.

## Assigning ID numbers

ID numbers are similar to nicknames for each grade item. In a calculation, instead of referring back to a whole assignment name, we can substitute it for it's ID number which becomes a lot easier. Think of it as substituting 143 as X and then using X for various math problems.

ID numbers on the bottom of the page. Use simple to remember numbers or variables like 1, X, or Quiz1. Remember to click "Add id numbers"!

## Understanding calculation functions

Click the yellow question mark next to the word "Calculation". This will bring a pop-up explaining the various functions that can be used in calculations and how to use them.

Every calculation must start with an equal sign (=). Following is a list of the functions supported by the calculation. The comma (,) character is used to separate arguments within function brackets. The comma can also be used to separate different functions. (The separator character could be a semicolon (;) in other languages, see below).

• average([[item1]], [[item2]]...): Returns the average of a sample
• max([[item1]], [[item2]]...): Returns the maximum value in a list of arguments
• min([[item1]], [[item2]]...): Returns the minimum value in a list of arguments
• mod(dividend, divisor): Calculates the remainder of a division
• pi(): Returns the value of the number Pi
• power(base, power): Raises a number to the power of another
• round(number, count): Rounds a number to a predefined accuracy
• sum([[item1]], [[item2]]...): Returns the sum of all arguments
• an asterisk (*) gives the product of two items: [[item1]]*[[item2]]

A number of mathematical functions is also supported:

• sin
• sinh
• arcsin
• asin
• arcsinh
• asinh
• cos
• cosh
• arccos
• acos
• arccosh
• acosh
• tan
• tanh
• arctan
• atan
• arctanh
• atanh
• sqrt
• abs
• ln
• log
• exp

## Making your calculation

Example calculation

Back on the calculations page, start typing the various functions and the ID numbers chosen for your calculation.

1. Start with an equal sign (=)
2. Choose a function; Example: =sum()
3. Plug in your ID numbers enclosed in 2 hard brackets; Example: =sum([[item1]][[item2]][[item3]])
4. Separate each ID number with a comma; Example: =sum([[item1]],[[item2]],[[item3]])
5. Weighted grade calculations: =sum([[1]]*0.3,[[2]]*0.6,[[3]]*2)
6. Click the "Save Changes" button.

## Calculations when user language is not English

Calculation formulas use decimal and list separators as defined in each language pack.

The decimal separator (a symbol used to mark the boundary between the integral and the fractional parts of a decimal number) is a point (.) in English. In other languages it may be a comma (,).

The list separator (a symbol used to separate a list of ID numbers in square brackets) is a comma (,) in English. In other languages it may be a semicolon (;).