The Number Of Natural Numbers Which Are Smaller Than 2 × 108 and Which Can Be Written By Means Of The Digits And 2 Is ………..

Let S = {1, 2, 3, ... n}. if X denote the set of all subsets of S containing exactly two elements, then the value of   

Let a be a factor of 120, then the number of integral solution of x₁x₂x₃ = a is 

There are 15 points in a plane of which exactly 8 are collinear. Find the number of straight lines obtained by joining there points.   

If n is the number of ways in which an examiner can assign 30 marks to 8 questions, giving not less than 2 marks to any quation find n/40.

Find the number of rectangles that you can find on a chessboard.

Find the number of integers greater than 7000 that can be formed with the digits 3, 5, 7, 8 and 9, no digit being repeated.

Ten persons, amongst whom are A, B and C, are to speak at a function. If n is the number of ways in which it can be done if A wants to speak before B, and B wants to speak before C find n/800.

Find the largest  such that 

Find the largest integer n for which 35! Is divisible by 3ⁿ.

Find the exponent of 2 in 50!?