How to recognise fake 100 RMB china money?

If there is no serial numbers on the middle right side of the 100 RMB china note, is it a real or fake one? I have the rest of the notes that I changed from the bank having a series of numbers on the middle right side of the note but some notes do not have. Please advise. thanx!|||Feel for the ridges at the bottom right of Maos portrait and look for the watermark If they are not there its a fake. Alternatively ask a Chinese person to teach you.|||Check the year it was made. There are new and old in circulation and they look the same. As long as it feels like proper paper money it should be fine.