Section 8,5,1: Arithmetic

 Arithmetic expressions contain numeric data such as variables,
 record elements, array elements, constants, function references,
 and arithmetic expressions enclosed in parentheses.  The expression
 evaluates to a numeric value.  The numeric operators are as
 follows:

      Operator    Ranking     Description
      -------------------------------------------------
         **        1          exponentiation (evaluated
                                  right to left)
         *         2          multiplication
         /         2          division 
         +         3          addition
         -         3          subtraction        

 You can use parentheses to force an order of evaluation.