Cool Magic Square Trick

Today I will talk about a very exciting and cool trick regarding magic square. Once you learn this trick, everybody will definitely acknowledge you as a great math magician ;)
Let's get started then,

First choose a participant. Ask him/her to select a 2 digit number between 22 and 99. Suppose he choses the number 50. Now I will construct a 4x4 magic square with different unique numbers and make him/her believe that I'm the greatest math magician :D
I will now take a pen and paper, draw a 4x4 grid and fill up the grid with some random numbers like this:

Well see, every number is random and unique. If you calculate the sum of every column or every row, even the diagonals, you will see the sum is 50 ! And that is your chosen number. If you take the sum of the numbers of the 4 corners, it will be 50 ( 30+7+4+9 = 50 ).
if you take any 4 square inside the grid, the summation of numbers there will be 50. Don't believe? Check yourself :P

Ok, but the trick doesn't end here actually. If you take any 9 square (3x3) and take the summation of 4 corners for that square, the sum will also be 50 !

Check the red colored tiles and see the magic yourself. Cool , right? And I can do this all
day with different numbers ;)
And even this is also possible:

The red and blue tiles sum is also 50! Well there are 28 different combinations where we can get the desired value.
Okay, let's reveal the trick behind the scene. First think of your magic square like this in your mind:

These four blocks are our magic blocks that will determine the outcome. Remember this by heart and randomly place numbers to other 12 blocks to confuse your partner. But you aren't doing it randomly, are you? ;) The greater the magician, the innocent he looks, so you have to be really smart and innocent to pull this off :P
Well, just fill the 12 blocks like this each and everytime:

You can remember this through some practice of course. Well it is essential for every magician to practice, so it's alright for you to do so. Look we didn't fill up the A, B, C, D blocks. We only placed the numbers from 1 to 12 here. And remember, everytime these 12 numbers have to be placed like this exactly. Now we will fill up the 4 magic blocks with four different magic numbers. How we will generate these magic numbers? Here is the answer:

A : Subtract 20 from the given number. The number given was 50. So I get 50 - 20 = 30 for the block A.
B : Subtract 1 from A, so we get 30 - 1 = 29.
C : Add 2 with A, so we get 30 + 2 = 32 for C.
D : Add 1 with A, so we get 30 + 1 = 31 for D.

Thank you for reading this. Hope you enjoyed all.