Years ago, I was measuring an outdoor site with a "Stanley" 100 foot steel Reel-Tape, that my Grandfather had used in northern Michigan copper mines.

I was getting bizarre results and things were not quite lining up with my partner's measurements, that had been quickly done with a regular measuring tape.

I was slow to realize, that instead of 12 inches to the foot, the markings on my 'Grandpa's tape' were divided into increments of ten to the foot!

Mine Engineers measured with a decimal one foot scale. Each increment was 1/10th of a foot, instead of one inch!