It says one minus, or defect probability of one%, raised to the power of nine, which is about 91%., You notice here the power of the exponen, if I take just for the sake of illustration, if I take even the 99% probability of doing something correct and I have many, many steps, Say for the sake of argument, I have 50 steps in the process, my probability of producing something correct at the end of the process, my process yield, is about 60%. 