0:00:00.120,0:00:06.840 You have n numbers that must sum to 10. So your first number plus your second 0:00:06.840,0:00:14.524 number, plus all the way to the nth number, has to equal 10. You may choose a 0:00:14.524,0:00:19.470 certain number of values, these xi's, any way you wish. But then a certain 0:00:19.470,0:00:24.260 number of values are forced, so that they sum to 10. How many degrees of 0:00:24.260,0:00:27.754 freedom are there? Or in other words, how many values may you choose any way 0:00:27.754,0:00:30.579 you wish. This is tricky.