hey all.
I've thought about this a hundred ways and I can't figure it out.
So, answer please.

I was trying to figure out how to make a number system that uses only the letters A to Z, such that it counts this way:
A
B
C
....
Z
AA
AB
....
ZY
ZZ
....
AAA
AAB

and so on

The problem is, this doesn't seem to correspond to a number system like base 10, because there's no representation of a "0"
Like in a base 10 counts 123456789 10
so it seems the above system has A as 1, therefore, going XYZ AA
would be like counting in base 10 123456789 11

Right?
So how do I overcome this, to have a 1 to 1 conversion rate for base 10 numbers to this letter only system?
In other words, if I put in 1, I get A
if I put in 26, I get Z
if I put in 27, I get AA.

I just can't figure it out.
Anybody?
Thanks
Wengang