let arg ...
       Evaluate each arg as an arithmetic expression.  See the  section
       `Arithmetic  Evaluation'  in  zshmisc(1)  for  a  description of
       arithmetic expressions.  The exit status is 0 if  the  value  of
       the  last  expression  is  nonzero, 1 if it is zero, and 2 if an
       error occurred.
