There must be a story in here. Tell us.
Some might say I'm being unfair to the ruler, but here goes:
Near the start of the exam I had to measure some distances. One of them was too long for my trusty Radio Nav plotter, so I used my nav ruler for the first time. It was about 6 inches long, so that last mark on the end had to be 60 nm, didn't it...
At last I came to a multiple choice answer which was impossible given my distances, and I went back and reworked the paper. Quite stressful, as I recall.
The moral is RTFR - Read The ****ing Ruler.