You may simulate operations with decimals using only integer numbers in a very simple way. For example:
@echo off
set /P "wcexpt=Enter value: "
rem Get 5% of wcexpt:
set /a percent=wcexpt * 5
rem Show result:
echo The 5%% of %wcexpt% is %percent:~0,-2%.%percent:~-2%
Output:
C:\> test
Enter value: 1234
The 5% of 1234 is 61.70
Of course, a much more detailed simulation that include all arithmetic operations is possible. See this post for further details.