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?

I add 5 to 9 and get 2. The answer is correct, so what am I?

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?

Look at the below sequence of letters and tell us what the next letter should be:

O T T F F S S ?

The more of this there is, the less you see. What is it?

Can you count the number of lines in the below picture?

Can you solve the below tricky visual equation?

Here is a Swiss Cross. You have to make two straight cuts in the figure so that it is divided into four congruent pieces. Also, you should be able to join these pieces into a square then. Can you accept this challenge?

Chef Andrea has to light the kitchen stoves to open her restaurant for the day. There are three stoves in the kitchen: A glass stove, a brick stove, and a wood stove. She only has one match. Which does she light up first?

This puzzle is for Harry Potter fans. Do you know why Tom Riddle is called Lord Voldemort?