There are 20 books on Algebra and Calculus in one library. For the greatest number of selections each of which consists of 5 books on each topic. If the possible number of Algebra books are N, then the value N/2 is __________.

The number of n digit numbers which consists of the digit 1 and 2 only if each digit is to be used atleast once is equal to 510, then n is equal to ________.

There are 3 books of mathematics, 4 of science, and 5 of literature. How many different collections can be made such that each collection consists of one book of each subject.

The number of selection of n objects from 2n objects of which n are identical and the rest are different is

Today morning I arranged the books in the almirah of my room. In each shelf I arranged books equal to the number of shelves of almirah. But 5 books remained out of the almirah. If toral number of book are 86, Let's find the number of shelves of the almirah.

If N is the number of ways in which 3 distinct numbers canbe selected from the set {3^1,3^2,3^3, ,3^(10)} so that they form a G.P. then the value of N//5 is ______.

If the numbers n – 2, 4n – 1 and 5n + 2 are in A.P., find the value of n.

if n objects are arranged in a row then the number of ways of selecting three of these objects so that no two of them are next to each other is

There are 3 men and 7 women taking a dance class. If N ils number of different ways in which each man be paired with a women partner, and the four remaining women be paired into two pairs each of two, then the value of N//90 is_________.

If the number of selections of 6 different letters that can be made from the words SUMAN and DIVYA so that each selection contains 3 letters from each word is N^2, then the value of N is________.

The value of the total number of 70 notes (currency) is Rs.590 , in which there are notes of Rs10 and 5. Find the number of each notes.