In a town, the car plate numbers contain only three or four digits, not containing the dit 0. What is the maximum numbers of cars that can be numbered?

The number of 3- digit numbers containing the digit 7 exactly once :

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

The maximum number of electrons that d-orbital can contain is

Decimals places the number of digits contained in the decimal part of a decimal number is known as the number of decimal places.

The number of n-digit numbers which contain the digits 2 and 7, but not the digits 0,1,8,9, is

Find the number of n digit numbers,which contain the digits 2 and 7, but not the digits 0,1,8,9.

The number of different seven digit numbers that can be written using only three digits 1,2 E3under the condition that the digit 2 occurs exactly twice in each number.