What number comes next in the series?

5 15 5 18 5 24 14 20 _

The person who makes it has no need for it. He who purchases it does not use it. The person who does use it does not know they are. What is it?

Can you find out the total number of triangles in the given figure?

What is wrong in the below Picture?

A seven-year-old kid challenged his classmates that he can make the number one disappear by adding something to it.

How can he do that?

using four eights (8) and a one (1) and one mathematical symbol , create the number 100

Rumel, A detective who was mere days from cracking an international smuggling ring has suddenly gone missing. While inspecting his last-known location, you find a note:

710 57735 34 5508 51 7718

Currently, there are 3 suspects: Bill, John, and Todd. Can you break the detective's code and find the criminal's name?

The host of a game show, offers the guest a choice of three doors. Behind one is a expensive car, but behind the other two are goats.
After you have chosen one door, he reveals one of the other two doors behind which is a goat (he wouldn't reveal a car).

Now he gives you the chance to switch to the other unrevealed door or stay at your initial choice. You will then get what is behind that door.

You cannot hear the goats from behind the doors, or in any way know which door has the prize.

Should you stay, or switch, or doesn't it matter?

Place the numbers from 1 to 9 in the circles in a manner that each side of the triangle sums up to 17.

What has many teeth, but cannot bite?