Editing Troy weight (section)

===Troy grain===
{{main|Grain (mass)}}

There is no specific 'troy grain'. All [[imperial unit|Imperial systems]] use the same measure of mass called a grain (historically of [[barley]]), each weighing {{frac|1|7000}} of an avoirdupois pound (and thus a little under 65 milligrams).{{Efn|Because an avoirdupois pound weighs 7000 grains and a pound is [[International Yard and Pound Agreement|legally defined]] as having a mass of exactly 0.45359237{{nbsp}}kg (453.59237 g, 453592.37 mg), one grain weighs 453592.37/7000{{nbsp}}mg (or nominally  64.79891{{nbsp}}mg  to seven [[significant figure]]s,  but this would be an example of [[false precision]].)}}