Compress 2 digit to 1 digit....

Hi, if I have a string = '12' , is there any way to add-on the 2 digit so my string now become 3?

Homework?

erm... ya, kind of...
Do you have any ideas?

Not sure what you are asking but:
"12" would be ascii 49 50
If you add 1 to 50 this gives ascii 51 hence you now have 49 51 "13"

More info.
Is this a test question?

.

I'm exploring the hash function, but the encrypted data is too long for some purpose so I was wondering if there is way to compress it to shorter form...