RandGeometric(probability,number)

Generates number random geometric trials.  RandGeometric returns the number of attempts before a success where the probability of success on each attempt is probability.

For example, how many rolls of a die does it take to roll a 6?

You can simulate this problem thirty times using RandGeometric(1/6,30) and you might generate the following data.

16, 3, 6, 9, 7, 10, 10, 3, 5, 11, 1, 9, 2, 6, 5, 7, 20, 21, 4, 2, 5, 5, 2, 10, 6, 2, 13, 1, 1, 10

Note:  If you type decimals using a comma (eg 3,2) you should enter this formula as RandGeometric(1/6; 30) - using the ; as a separator