Calculating the absolute value of a number is one of the various mathematical functions available to use on your data.

If you take a close look at the Number_of_rentals column, you will notice that some of the numbers have a negative value.

These cells are not marked as incorrect in the quality bar because they still fit the
semantic type automatically set as `integer`

. Nevertheless, this is
unusable data. As a consequence, you are going to apply a function to remove the
negative sign for all these numbers.

To calculate the absolute value of your data, proceed as follows:

## Procedure

## Results

Your preparation now displays all your data again. If you take another look at the statistics box for the Number_of_rentals column, you can see that the minimum value is now 0 instead of -10. You have thus improved the quality and usability of your data.