Same Digit Consecutively
Probability
Level
1
How many distinct positive integers are there of digits in which no two consecutive digits are the same?
Assumption :
- The leftmost digit of a -digit number is non-zero.
The answer is 59049.
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1 solution
First digit:
You can use any digit except 0: 9 possible digits
Second digit:
You can use any digit except for the first digit: 9 possible digits
Third digit:
You can use any digit except for the second digit: 9 possible digits
Fourth digit:
You can use any digit except for the third digit: 9 possible digits
Fifth digit:
You can use any digit except for the fifth digit: 9 possible digits
9* 9* 9* 9* 9=59049