While talking about probability with mainland Chinese students I asked what they say for heads and tails on a Chinese coin. I was tossing a one Yuan coin, and they decided I could say in English "flower" and "number." Okay. I did not want to go on talking about language so I did not ask what they actually say in Chinese. But when I search on line I do not find anything like this. I mostly find 正面 and 反面, which are also what Google Translate offers.
I wonder if 正面 and 反面 are just the technically correct expressions, like "obverse" and "reverse" in English, which most people never say.
Are there more common mainland expressions for the sides of a coin?