Going back to
cribble's post -
"Descend 2400..." vs "descend to 400.."
The controller's words "Descend Two Four Zero Zero" (correct in the phraseologies of the time) was the origin of the current use of "Thousand" in the altitude call. In today's words, it would have been "Descend to Two Thousand Four Hundred".
We live and we learn, it's surprising even today to hear many pilots, and some controllers, not using the "Hundreds" component of F/L 200,300 etc., but still using zeros.
Users of Australian airspace will note that there is no Runway 02 or 20 in the country, even if the runway direction indicates that it should be so. 01/19 or 03/21 is used instead, whichever is closer to the actual. This originated from an accident many decades ago when 02 was interpreted (fatally) as 20 by a pilot.
I'd be interested to know if the American practice of not using the preceding zero for runways such as 06, has lead to a significant incident or accident.