What number should come in place of the question mark below?

Three men in a cafe order a meal the total cost of which is $15. They each contribute $5. The waiter takes the money to the chef who recognises the three as friends and asks the waiter to return $5 to the men.

The waiter is not only poor at mathematics but dishonest and instead of going to the trouble of splitting the $5 between the three he simply gives them $1 each and pockets the remaining $2 for himself.

Now, each of the men effectively paid $4, the total paid is therefore $12. Add the $2 in the waiters pocket and this comes to $14. Where has the other $1 gone from the original $15?

Which is the smallest number that you can write using all the vowels exactly once?

How can you drop a raw egg from a height onto a concrete floor without cracking it?

Decode the below four famous ciphers:

8P of the SS
1M of the E
1S of the SS
60M in 1H

I am the fastest animal but cannot climb the tree. What am I?

Analyze and find the missing item in the sequence:
16, 06, 68, 88, __, 98

My friends called me Iron59 because my parents are a chemist and a mathematician. What is my real name?

How many triangles are there on the puzzle below?

Find the next number in the following series:
6, 14, 26, 98, __?