easy hash algorithm to use without computer I am searching for a simple hash algorithm(s) which can be used to calculate relatively secure hash without using of any computer. Some requirements:


use only simple arithmetics operations (+ - / *, maybe mod and abs) 
base of 10 (letters can be substituted with groups of 2 digits), not binary
short time of calculations (limited number of operations per hash and limited number of digits per number) 
simple calculation (normal person should be capable of memorize it)
if whole calculation could be done in memory, it would be a plus but it is not necessary
only short messages will be hashed (maximum 50 - 100 characters, about 35 on average)
relatively secure (of course no modern computers will be used to reverse / find a conflict)


Edit:

there is similiar question here: 
 Is there a simple hash function that one can compute without a computer?, but all responses seems to be too complicated to fit in my requirements
There has been a similar question. The accepted answer there refers to Manuel Blum's HCMU hash function.

Check out Manuel Blum's human computable hash function. He calls it HCMU for Human Computable Machine Unbreakable.
He claims you have to spend an hour memorizing the technique and then you can apply the has function in about 20 seconds without even using pencil and paper.

I have found an implemention of this function here, in just over 60 lines of Python code. Unfortunately I cannot find any paper on it on the go and the link in that other question is broken.