Question 940452: airtel wants to make mobile phone numbers consisting of the
digits 0,1,2,3,4,5,6,7,8 and 9 how many numbers are possible if: i.The first digit is 0 and they are to consist of only eight digits?
Answer by Edwin McCravy(20054)   (Show Source):
You can put this solution on YOUR website!
0,1,2,3,4,5,6,7,8 and 9
1 way to pick the 1st digit (as 0).
9 ways to pick the 2nd digit.
8 ways to pick the 3rd digit.
7 ways to pick the 4th digit.
6 ways to pick the 5th digit.
5 ways to pick the 6th digit.
4 ways to pick the 7th digit.
3 ways to pick the 8th digit.
1×9×8×7×6×5×4×3 = 9!/2! = 181440
Edwin
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