Find the number of natural numbers which are less than `2xx10^8` and which can be written by means of the digit 1 and 2.

The mean of first 10 natural numbers.

The number of natural numbers less than 7,000 which can be formed by using the digits 0, 1, 3, 7, 9 (repetition of digits allowed) is equal to

Find the number of integers which lie between 1 and 10^6 and which have the sum of the digits equal to 12.

Find the number of three-digit numbers which are divisible by 5 and have distinct digits

Find the sum of all three-digit natural numbers, which are divisible by 7.

The number of 10 digit number that can be written by using the digits 2 and 3 is

The number of five-digit numbers which are divisible by 3 that can be formed by using the digits 1,2,3,4,5,6,7,8 and 9 , when repetition of digits is allowed, is

Find number of four-digit numbers in which repetition is not allowed.