00:01
So in this question we can see we need two digits, two letters and another three digits.
00:08
So we need five digits and two letters.
00:17
And also as required, we need no letters or digits are repeated.
00:23
So we need five distinguishable digits and two distinguishable letters.
00:29
And in this question we do care about the order.
00:32
So that is a permutation denoted by p, right? so we peak five degrees from the total 10 degrees because it's 0 to 9, right? and times the permutation of two letters from 26 letters.
01:05
So we can see this formula equals to the factorial of 10.
01:23
Over the factorial of 10 minus 5.
01:27
So that is 5 times the factorial of 26 over the factorial of 26 minus 2.
01:38
That is the factorial of 24...