A four digit number is called a doublet if any of its digit is the same as only one neighbour. For example, 1221 is a doublet but 1222 is not. Number of such doublets are

How many four digit numbers are there with distinct digits?

Number of four digit numbers in which at least one digit occurs more than once, is :

Let ' m ' denotes the number of four digit numbers such that the left most digit is odd, the second digit is even and all four digits are different and ' n ' denotes the number of four digit numbers such that left most digit is even, second digit is odd and all four digit are different. If m=nk, then k equals :

Number of 6 digit numbers that can be formed using digit 2 two times and the digit 5 four times is

How many unequal 5 -digit numbers can be formed using each digit of the number 11235 only once?

A two digit number is 4 times the sum of its digits and twice the product of its digits. Find the number.

Number of three digit numbers such that atleast one of the digits is 9 , if repetitions allowed is

A two-digit number is 4 times the sum of its digits and twice the product of the digits. Find the number.

How many four digit numbers can be formed using digits 1, 2, 3, 4, 5 such that at least one of the number is respeated?

Write all 3-digit numbers using the digit 2, 3, 5, taking each digit only once.