00:01
For this question, we asked how many five -digit numbers can be formed using the digits 1, 2, 3, 4, 5, 6, 7 if repetition of digits is not allowed.
00:11
So here, the order matters.
00:13
So the order matters.
00:17
So essentially, we were given 1, 2, 3, 4, 5, 6, 7 possibilities.
00:21
So out of the 7 possibilities, we need to permute 5 times.
00:26
So how many 5 digit permutations can be formed using 7 possible digits? so the rule for permutations is going to be the number factorial over, is going to be over n minus r.
00:46
So the total number minus a total possibility.
00:48
So it's going to be, we'll just say n minus r factorial...