The special number
is 25, which corresponds
to the letter y. Yellow
is the most common color that begins with y. 

If B represents the number of the birth month, each
step can be written
as shown in the table below. 


Step 
Algebraic
Representation 
Take
the number of your birth month 
B 
Add
32 
B
+ 32 
Add
the difference of 12 and the number of your birth
month 
B
+ 32 + (12 – B) 
Divide
by 2 
B
+ 32 + (12 – B)
2 
Add
3. 
B
+ 32 + (12 – B) + 3
2 
The final step can be simplified as follows:
B
+ 32 + (12 – B) + 3
2 
= 
(B
 B) + (32 + 12) + 3
2 

= 
0
+ 44 + 3
2 

= 
22
+ 3 

= 
25 
Therefore, no matter what number you choose for B, it
is added and then subtracted and does not affect the answer.
The answer is always 25. The 25th letter of the alphabet
is y. The most obvious color beginning with y is yellow.
