Which alphabet letter is a question?

In a stable, there are men and horses. In all, there are 22 heads and 72 feet. How many men and how many horses are in the stable

There are forty elephants and they have forty-fore heads. How can this be possible?

Find a 9-digit number, which you will gradually round off starting with units, then tenth, hundred etc., until you get to the last numeral, which you do not round off. The rounding alternates (up, down, up ...). After rounding off 8 times, the final number is 500000000. The original number is commensurable by 6 and 7, all the numbers from 1 to 9 are used, and after rounding four times the sum of the not rounded numerals equals 24.

What does it mean?

What has many keys but can’t open a single lock?

In the following series, a set of numbers is progressing with a particular pattern. Can you deduce that pattern and find the missing set?

(2 + 6), (21 + 6), (58 + 6), (119 + 6), ___

It belongs to you, but other people use it more than you do. What is it?

How can you take 2 from 5 and leave 4?

Can you arrange four 9's and use at most 2 math symbols, to make the total 100?