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?

Can you complete the sequence?

192, 021, 222, 324, 252, 627, 2__, 9__?

A certain street contains 100 buildings. They are numbered from 1 to 100. How many 9's are used in these numbers?

In the image below, you can see two glasses and two matchsticks.You need to move four matchsticks in such a manner that the crosses come inside the glasses. Note: you cannot move the crossed.

I make a loud sound when I’m changing. When I do change, I get bigger but weigh less. What am I?

A boy purchased a book from a bookkeeper and gave him $100.
The cost of the book is $50 but the bookkeeper has no change, so he gets the change from the next shop and returns the boy his $50.

After some time the next shopkeeper came with the $100 note and told the bookkeeper that the note was a fraud, so he took the money back.

How much loss did the bookkeeper face?

The day before yesterday I was 25 and the next year I will be 28. This is true only one day in a year. What day is my birthday?

Until it is measured, not known. Yet how you miss it when it has gone. What is it?

Move four matchsticks to the below square to form three squares?

Different lights make me strange by changing me into different sizes. What am I?