A parameterised exercise will come with different values each time one practices.

The advantage is that you only have to create an exercise once. Our program will then randomly select new values each time you view the exercise.

It's quite easy to add parameters (variables) to an exercise.

First start by choosing an existing exercise (or create a new one). Then go to 'more' in the top right and select 'toggle parameterisation'.

A new field will appear underneath the feedback fields. Click on '+ new placeholder' and create a new parameter.

You can select what the possible values are for these parameters.

At this moment, there are three different parameter types:

- Random
- Range
- Formula

You can use the random and range types as input values.

Then you can create other parameters that enter those values into a formula. To relate the answer to the parameters, just create another formula parameter to denote the answer.

Once you have defined the parameters, you can use them in the description, question, answer and feedback fields.

Now add the parameters to your exercise and hit preview to view the result.

Finally: you can also add **Conditions**. This is especially useful for exercise in Probability, when a certain probability cannot be greater than another probability.

Do make sure the conditions that you enter make sense. When the engine cannot compute your commands, it will stop after 30 seconds and return an error.