A little hack to make a pocket Inch <-> mm converter : re-use a currency converter calculator
I don't know for the US, but in Europe, it is easy to find some cheap little pocket currency calculators that convert Euro in any currency. You can program the exchange rate of course.
So in this article, I show how I modified one to obtain an efficient Imperial/metric converter (mm <-> Inch) :
La Belle Note - Convert inches into millimeters
In this particular case, efficiency means having the bare minimum of operations to do in order to obtain your result, which is typing you entry number, and hit one single touch, for both directions.
Here is a picture of the converter :
I have programmed the right conversion rate, and I have modified the keys for them to show explicitely "->mm" and "->Inch". See the article.
This is THE tool I really use everyday, it's always beside my computer.
see the next post to see how I addressed the fractional inches issue.