Can you make numbers like 24, using numbers 3,3,7 & 7 with any arithmetic operator?

There is a square of a particular number which when doubled, becomes 7 more than its quarter.

Can you find the number?

I am white when I am dirty, and black when I am clean. What am I?

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?

Find three numbers such that

* When we multiply three numbers, we will get the prime numbers.
* The difference between the second and the first number is equal to the third and second.

Count the Triangle in the figure given below:

You along with your friend are standing in front of two houses. Each of those houses inhabits a family with two children.

Your friend tells you the below two facts:
1) On your left is a family that has a boy who likes accounts but the other child loves science.
2) On the right is a family with a seven-year-old boy and a newborn baby.

You ask him, "Does either of the family have a girl?"

To this, he replies, "I am not quite sure. But can you guess that? If you are right, I will give you $500."

Which family do you think is likely to have a girl?

What has 88 keys?

That attorney is my brother, testified the accountant.

But the attorney testified he didn't have a brother.

Who is lying?

A thief is convicted in Mexico. He gets the death penalty. The judge allows him to say the last sentence to determine how the penalty will be carried out. If the thief lies, he will be hanged, if he speaks the truth he will be beheaded. The thief tells the last sentence and to everybody's surprise some minutes later he is set free because the judge cannot determine his penalty. What did the thief say?