" How many six-digit numbers contain exactly four different digits? "

If the number of 6 digit numbers which contain exactly 4 different digits such that exactly one digit repeats is k(7!) then find k

How many 3-digit number have exactly one of their digits as 5?

How many 3-digit number have exactly one of their digits as 5?

Given the digits 1,2,3 and 8 How many four digit numbers can be formed using the given digits?

How many five-digit numbers can be made having exactly two identical digits?

How many five-digit numbers can be made having exactly two identical digits?

How many five-digit numbers can be made having exactly two identical digits?

How many five-digit numbers can be made having exactly two identical digits?