You might not be able to actually do what you want,
but you may be able to approximate the desired results by multiplying and dividing
by powers of 10, and doing string manipulation.
For example, consider this `divide.bat`

:

```
@echo off
set /a q=%1 * 1000 / %2
echo q = %q:~0,-3%.%q:~-3%
```

`%`*variable_name*:~*start_pos*,*length*%

is Command Prompt variable substring notation.
Negative numbers are relative to the length of the string (variable value);
a missing *length* means the rest of the string.

Here are some sample results:

```
divide 8 4 -> q = 2.000
divide 6 4 -> q = 1.500
divide 3 4 -> q = .750
```

In the last example (*your* example), `q`

is actually 750.
If you want to compute 75% of something, either

- multiply by
`%q%`

and divide by 1000, or
- multiply by
`%q%`

and remember that the result is 1000× its true value,
and you need to use the substring notation when you display it.

`SET /A`

only works on integers. So there is no way to get`0.75`

using that – Nifle Jun 16 '11 at 6:54