Question

The number of n digit numbers,no two consecutive digits being the same is

Answer 1

Step-by-step explanation:

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Answer: n!

Solution: Assuming that no two consecutive digits are the same, the number of n digit numbers, is n!.

For example, 4! = 4.3.2.1

Answer 2

There are {0,1,2,10}, 10 different digits of which 1

st

place is filled in 9 ways, 2

nd

place in 9 ways (since 0 can be included and first digit is not repeated) and so on n times.

Thus number of ways is =9×9×____=9

n