Suppose your cell phone uses a 4-digit personal identification number (PIN) to lock it from use.
How many PINs can you choose to lock your cell phone?
when you have a four digit pin number. Um, it's not just any four digits. There's a specific order that you have to enter those four digits. So that's gonna make this a permutation. Of the 10 digits that we have on our phone, we're gonna choose four of them. So that means that we have 5000 40 possible PIN numbers that we can choose.