Hey JAARule,
http://www.faa.gov/air_traffic/publi...M/aim0402.html
Brush up on that before your next flight.
three five ohh, is not standard phraseology and it not used by ATC.
But I do dare you to challenge some old-skool crusty pilot saying "three five ohh" on the radio on your next US Flight. Would make a great YouTube video. Maybe even join the ASR hall o' fame.
Imagine this ASR,
"Another aircraft read back a clearance to climb and maintain "tree fife zero" as "three fife ohhhh. It posed no threat or safety to anyone else, but was highly offensive."