Zhengzhou long distance bus from Luoyang

The bus is not distinguish by number. You can just go to Peony Square (Jianxi District) to take it. The first bus departs at 04:30. Then it runs from 06:00 to 17:00 hourly. The duration is about 2.5 hours.

Great and this goes to Zhengzhou airport? If i want to know the number do you have any suggestions speaking to someone at tourism center if there is one or any page that says?

Emma is right that you should take the bus at Peony Square (Mudan Guangchang), Jianxi District. And the buses can take you to Zhengzhou Airport directly. But as I know, the first bus depart at 04:00 and then they operate from 06:00 to 18:00 hourly.
And definately, there is no an exact number on the buses. But it's easily to be spotted in the square. Or you can ask a local person around you. Relax!

Much appreciated help from both of you Emma and Nick!!

One more question i forgot to ask, Buses overall in China can they let you buy ticket in the bus for cash or must you buy a ticket station first?

Well, you have to buy a ticket at the station in cash.