How many 3-digit positive integers are there, where each digit is positive, and no 3 adjacent digits are same?  Choose the correct choice from the following answers
A) 1236	B) 504	C) 4096	D) 4608	E) 6561
First digit.. 9 posibilities   Second digit, 8 possibilities   third digit, 7 possibilities     9*8*7= 
<gadget id="calculator">  9*8*7</gadget>
<output>504</output>
504.   504
<result>B</result>
How many 3-digit positive integers are there, where each digit is positive, and no 3 adjacent digits are same?