Question: The number of ways in which we can arrange the digits 1, 2, 3,.......9 such that the product of five...

Question

The number of ways in which we can arrange the digits 1, 2, 3,.......9 such that the product of five digits at any of the five consecutive position is divisible by 7 is-

Answer 1

Solution

For five digits at any of the five consecutive positions to divisible by 7, if the 7 is the 5^th digit, the rest of 8 digits can be arranged in 8! ways.