How can math tools you detect errors or inaccuracies in data

If you are talking about using rulers, protractors, compasses, etc. then here's my answer; 
If you were to use, let's say a ratio, and you calculated it with a calculator and some scratch paper, there's always a chance of human error (like accidentally pressing the wrong key on your calculator) and that can throw off your whole answer. But if you were to use math tools, then you have a better chance of being more precise and specific with your data (but then again even with the tools you can make human errors, so don't rely completely on them). 

He savage. (i actually don't know)