Question

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

Solution

Correct option is

1296

There are 9 horizontal and 9 vertical lines on a chessboard. To form a rectangle we require two horizontal and two vertical lines. Thus, the number of rectangles on the chessboard is (9C2) (9C2) = 1296.

SIMILAR QUESTIONS

Q1

The number of times the digit 3 will be written when listing the integers from 1 to 1000 is

Q2

The number of positive integers n such that 2n divides n! is

Q3

A class contains 4 boys and g girls. Every Sunday five students, including at least three boys go for a picnic to Appu Ghar, a different group being sent every week. During, the picnic, the class teacher gives each girl in the group a doll. If the total number of dolls distributed was 85, then value of g is    

Q4

The sum of the factors of 9! Which are odd and are of the form 3m + 2, where m is a natural number is 

Q5

Sum of all three digit numbers (no digit being zero) having the property that all digit are perfect squares, is

Q6

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

Q7

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

Q8

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

Q9

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.

Q10

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.