Rational Solver
0 votes
19 views
Find the number of all $20$-digit integers in which no two consecutive digits are the same.
in Discrete Mathematics by Expert | 19 views

1 Answer

0 votes
Best answer
The first digit can not be $0$ and so for the first digit we have 9 options (from $1$ to  $9$). Now we have to choose the next digit in such a way that it is not the same as the previous one.  Thereofore on choosing the next digit we can have 9 options as well, (because we can choose any number from $0$ to $9$ except the previous one). Therefore, each of the remaining 19 digits can only have 9 options. Therefore there are $9\times 19^9$ numbers are available of the given type.
by Expert
Welcome to Rational Solver, where you can ask questions and receive answers from other members of the community.
64 questions
22 answers
2 comments
1,801 users