More and more, I use Latex as scratch paper, sometimes to develop numerical (counter-)examples. I often find it much cleaner and better organized than if I rely on actual pen an paper.

Numerical examples are usually a “back and forth” kind of business, with many moving parts, and you trying to find the numbers that “make it work here” without “changing things there”.

So finding the right combination of numbers often requires a lot of simple (but error-prone) calculations. In that matter too, Latex can help save time and prevent mistakes.

With pen and paper, you would usually (1) write down your arithmetic (e.g., (1/3)*57 + (1/4)*23 + (5/12)*20), (2) use a calculator or spreadsheet to perform the calculation, and (3) write down the result on your sheet of paper.

There are many ways to make mistakes in that process.

Latex allows you to reduce the chances of mistakes, and save you some time going back and forth between pen, paper, and calculator. Have a look at https://tex.stackexchange.com/questions/30081/how-can-i-sum-two-values-and-store-the-result-in-other-variable. Very much like you would if you were using Markdown, Latex lets you (with the help of a particular package), (1) write down your arithmetic and (2) simply ask LaTex to compute the result.

The code looks something like this:

`\documentclass{article} \usepackage[nomessages]{fp}% http://ctan.org/pkg/fp \begin{document} \FPeval{\result}{clip( (1/3)*57 + (1/4)*23 + (5/12)*20 )} $(1/3)*57 + (1/4)*23 + (5/12)*20 = \result$ \end{document}`

As illustrated in https://tex.stackexchange.com/questions/30081/how-can-i-sum-two-values-and-store-the-result-in-other-variable, you can easily round decimals to your liking:

`\documentclass{article} \usepackage[nomessages]{fp}% http://ctan.org/pkg/fp \begin{document} \FPeval{\result}{round( 100/3, 1 )} $100/3 = \result$ \end{document}`