What is the next number in this matchsticks series riddle?

Two boys wish to cross a river. The only way to get to the other side is by boat, but that boat can only take one boy at a time. The boat cannot return on its own, there are no ropes or similar tricks, yet both boys manage to cross using the boat.

How?

Who has married many women but was never married?

Twenty frogs are sitting on a log floating on the surface of a river. Two of them decide to jump off into the water.

How many frogs are there on the log at this moment?

They are three errirs in this question. Can you find them?

Count the number of triangles in the below picture?

How many pluses should we put between the digits of 987654321 to get a total of 99, and where?

In the figure, you can see nine stars. What you have to do is connect all of them by using just four line and without lifting your hand i.e. in a continuous flow.

How can you leave a room with two legs and return with six legs?

Find out the number of circles in the given picture having Illusion