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

If,

20 % 5 = 24

21 % 7 = 33

42 % 6 = 67

Then;

66 % 6 = ?

What part of the chicken has the most feathers?

An office is divided into 8 cubicles. How many of the cubicles are painted if only 1/8 of the cubicles are painted?

If 1+9+8=1, what is 2+8+9?

Can you find the missing letter in the sequence?
S - T - I - L - ? - T - F - Y - C

What is the next number in this matchsticks series riddle?

What number does the below three word/phrase identify and why?
1. Deck
2. Year
3. Singing in the Rain

There are three light switches outside a room. One of the switches is connected to a light bulb inside the room.
Each of the three switches can be either 'ON' or 'OFF'.

You are allowed to set each switch the way you want it and then enter the room(note: you can enter the room only once)

Your task is to then determine which switch controls the bulb?

A man desired to get into his work building, however he had forgotten his code.
However, he did recollect five pieces of information
* Fifth number + Third number = 14
* The fourth number is one more than the second number.
* The first number is one less than twice the second number.
* The second number and the third number equals 10.
* The sum of all five numbers is 30.

What is the code ?