4.4 Arithmetic ExpressionsThe Korn shell's let command performs arithmetic. ksh88 is restricted to integer arithmetic. ksh93 can do floatingpoint arithmetic as well. The Korn shell provides a way to substitute arithmetic values (for use as command arguments or in variables); base conversion is also possible:
4.4.1 OperatorsThe Korn shell uses arithmetic operators from the C programming language; in decreasing order of precedence.
4.4.2 Builtin Mathematical Functions (ksh93 only)ksh93 provides access to the standard set of mathematical functions. They are called using C function call syntax.
4.4.3 ExamplesSee the let command for more information and examples: let "count=0" "i = i + 1" Assign i and count let "num % 2" Test for an even number (( percent >= 0 && percent <= 100 )) Test the range of a value 
