How do I use basic batch math commands to come up with decimal answers?

Question

I am making a batch file so that I just tell it what kind of formula I need to use and it tells me what variables I need to input. Right now, I am coding it so that it will

Answer 1

For the task at hand you could work around the limitation by some kind of fixed-point arithmetics as in the followinf sample code:

set /p TriangleB=How long is the base of the triangle? (Don't put the unit, just put the number):
set /p TriangleH=What is the height of the triangle? (Don't put the unit, just put the number):
set /p TriangleAreaUnit=What unit is the triangle being measured in?:
set /a TriangleArea=%TriangleB% * %TriangleH% * 10 / 2
echo The area of the triangle is %TriangleArea:~,-1%.%TriangleArea:~-1% %TriangleAreaUnit%.
pause >nul
goto :EOF

What I am doing here is nothing but multiplying everything with 10, so the division by 2 does no longer procude a fractional part that would be lost; afterwards, the decimal separator is inserted by string manipulation operations.
This works only if the input numbers are integers. Of course you can extend that to more decimal figures; but you need to regard that the interim result does not exceed the signed 32-bit limitation.