How many times can you subtract the number two from the number fifty?

You have an empty wine bottle with a cork that has been secured at the top in a normal way. There is a metal ring inside the bottle that is suspended by a string.

How can you make the metal ring drop to the bottom if you are not allowed to touch anything - not the bottle, not the cork, not the thread and not the ring?

I throw two dice simultaneously.

What is the probability of getting a sum as 9 of the two numbers shown?

I’m tall when I’m young, and I’m short when I’m old. What am I?

Without looking at a calendar, within a minute name, a boy's name using 5 consecutive 1st letters of 5 consecutive months

Can you solve the below algebraic mathematical equation?

(J+O+I+N+T)3 = JOINT

How many triangles can you find in this given picture?

A man hijacks an aeroplane transporting both passengers(8 of them) and valuable cargo. After taking the cargo, the man demands nine parachutes, puts one of them on, and jumps, leaving the other eight behind. Why did he want eight?

Below, you will find the mathematical proof that 10 equals 9.99999?. But is that possible or there is something wrong about it? Can you find the error?

x = 9.999999...
10x = 99.999999...
10x - x = 90
9x = 90
x = 10

One is to three as three is to five and five is to four and four is the magic number.
What is the pattern?