Mod function in fast formula

Summary

Mod function in fast formula

Content

Hi all,

I need to know how do we use MOD function in fast formula.
Example:

ln_months_mod  = (100/10) ---->  10
ln_months_mod  = (200/10) ---->  20
ln_months_mod  = (130/10) ---->  13
ln_months_mod  = (123/10) ---->  10

Last one need to return as 12

So  I need, ln_months_mod  =  MOD  (123/10) 
like that

please help