To find the range of a set of data, follow these steps:

1. Arrange the data in ascending order (from least to greatest).

2. Find the minimum value (smallest number) in the data set.

3. Find the maximum value (largest number) in the data set.

4. Subtract the minimum value from the maximum value.

For example, consider the following set of data: 5, 12, 18, 20, 25.

1. Arrange the data in ascending order: 5, 12, 18, 20, 25

2. Find the minimum value: The minimum value is 5.

3. Find the maximum value: The maximum value is 25.

4. Subtract the minimum value from the maximum value: 25 - 5 = 20.

Therefore, the range of the data set is 20.