How can you make number one disappear by adding something to it?

At my favorite fruit stand,
an orange costs 18,
a pineapple costs 27,
and a grape costs 15.
Using the same logic, can you tell how much a mango costs?

Make eight squares by moving only two matchsticks.
Note- Square can be of different sizes.

Take 9 from 6, 10 from 9, 50 from 40, and leave 6.

How Come ??

A man is found dead with a knife in his back When the investigation is done. A chair lays beside him and the forensic team finds moisture around the body.

If he committed suicide, how did he do it?

I am a type of room you cannot enter or leave. Raised from the ground below, I could be poisonous or a delicious treat. What am I?

You may enter, but you may not come in. I have space, but no room. I have keys, but open no lock. What am I?

Which is the correct shadow of the bird?

You have two strings whose only known property is that when you light one end of either string it takes exactly one hour to burn. The rate at which the strings will burn is completely random and each string is different.

How do you measure 45 minutes?

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

Can you find the number?