Assume the length of one matchstick is 1 unit.
In figure 1 we used 12 sticks to form an area of 5 square units. In figure 2 we also used 12 sticks, but this time the area is 9 square units.
How would you create an area of 3 square units using 12 sticks and not breaking any of the sticks? This one is not so easy...!