The total number of natural numbers of 6 digits that can be formed with the digits 1,2,3,4, if all the digits are to appear in the same number atleast once is ?
As we want all these numbers to appear in the natural number, we first put these 4 digits into any 4 of the 6 places and arrange them in 6P4 ways.
Now remaining 2 places can be filled with any of the 4 numbers in 4*4 ways.
So total number of ways is 6P4 * 4*4.
Where am I going wrong ?