Consider all the six digit numbers that can be formed using the digits 1, 2, 3, 4, 5 and 6, each digit being used exactly once. Each of such six digit numbers have the property that for each digit, not more than two digits smaller than that digit appear to the right of that digit.
The examples of such numbers are 315426, 135462, 234651 ect.
Number of the six digit numbers having desired property is:
Best Answer
Hint: How many different places can the $6$ go? Once the $6$ is placed, how many different places can the $5$ go? Then keep going.