Question

The number of squares formed by 5 vertical and 4 horizontal lines (all are equispaced ) is _________

a) 60
b) 20
c) 40
d) 46

Answer 1

b) 20
==========

The number of squares formed by 5 vertical and 4 horizontal lines (all are equispaced) is 20.

Number of squares = 12 + 6 + 2 = 20.

Answer 2

To find ,

No. of squares formed by 5 vertical lines and 4 horizontal lines which are equally spaced.

Main solution :

The no. of sqaures formed = ( 4 × 3 ) + ( 3 × 2 ) + ( 2 × 1 ) = 12 + 6 + 2 = 12 + 8 = 20.

Note : Here in this question number of sqaures don't only consider the small sqaures inside the sqaure, but also several sqaures which are formed by grouping these basic ( small ) sqaures.