There are total of 16 squares.
How?
Lets count :-
Squares with side length equal to 1 matchstick: 9
Squares with side length equal to 2 matchsticks: 5(2+1+2)
Square with side length equal to 3 matchsticks: 1 (This is
difficult to find, and easy to miss)
Square with side length equal to 4 matchsticks: 1
So total number of squares = 16
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