I saw a discussion online recently where a young narrow gauge modeller was thrown to the lions for asking for confirmation that in OO9 4mm equalled a foot.
As one has come to expect on social media this person was mocked and condemned for their ignorance, and the lack of initiative for asking the question in a post rather than researching the answer themselves.
However it made me realise that those of us who scratch build or work from drawings on a regular basis probably take it for granted how many conversions and calculations me make as a matter of routine.
As well as scaling down the dimensions we also have to convert between metric and imperial repeatedly.
Even the scale I'm working in - 4mm - is a mix of the two.
So take, for example, a model I might decide to make of one of the FR's latest carriages.
These days they're designed using metric measurements, expressed in mm.
So my first task is to convert this to an figure in feet and inches and then scale it down and get a value based on 1 mil for each 3 inches.
(I'm not too proud to admit that a calculator is involved at this point.)
That is not the end of the process, either, because when I come to make my model - in metric - I'm building it using styrene strips from America which are sold according to imperial sizes.
So, for example, if I need a strip to be 1mm wide (a scale 3 inches) then I need to reach for the packet with strips that are 0.40 thou of an inch thick.
It's no wonder people who are relatively new to the hobby go online in search of answers, is it?