how to write divided function

hi
iam facing problem for divided (%) arthemtic function in for condition.
tell me reply and all the arthemtic function in one scripting .

It is usually called modulo arithmetic

#!/bin/ksh
echo $(( 13 % 2 ))
#  echo 51 / 17 | bc
3

or

#  echo "scale=3;50 / 17" | bc
2.941

HTH