Sorry to confuse you. My message is a hybridisation of 舌尖上的粵語, slang and jargon.
I estimate that the correct writing of "數壟" is "數洞" which represents counting number of holes. The coins of ching dynasty were with holes in the center. Counting number of holes is counting number of coins to pay the bill - 買飛.
To play showhand, we need to make the first bet (i.e. to put our money on the table) before we can get the first card out of five. This amount of money is called part. We need to inject more and more money until we can see the last card if we get the chance. 度度景點都要買飛 . Eventually, it might worth.