Replace the question mark with the number below given a simple math problem.

Women do it once a year after they turn 19 but men get to do it only once in a lifetime. What is it?

I get hot but I never sweat,
I cook food but I am not a chef,
I have a door but you can't enter me,
I have a light but I am not a lamp.
Who am I?

A man dies of old age on his 25 birthday. How is this possible?

What can run but never walks, has a mouth but never talks, has a head but never weeps, has a bed but never sleeps?

I have holes on the top and bottom. I have holes on my left and on my right. And I have holes in the middle, yet I still hold water. What am I?

Can you make the below equation true by using any three numbers from "1, 3, 5, 7, 9, 11, 13 and 15"?

( ) + ( ) + ( ) = 30

In the figure, you can see nine stars. What you have to do is connect all of them by using just four line and without lifting your hand i.e. in a continuous flow.

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?

Why did the Girl throw the butter out of the window?