Question

To access his bank’s ATM, Tom must choose a four-digit PIN. Any digit from 0 through 9 can be used in the PIN, but digits may not be repeated. How many possible PIN numbers are there?

Answer 1

Try using the permutations formulae - nPr

n = 10

r = 4

you should get the answer. I don't have calculator on me and I'm lazy searching an online calculator. cheers