Riddle 7

A man wanted to go into the night club. He went up to a guard standing at the front door. "Whats the password?" the guard asked him. The man did not know. He hid behind bushes to figure out. Another man went up to the guard. The guard said twelve. The man said six. He was let in. After that, another man came up. The guard said six, the man said three. He was also let in. The man hiding was feeling satisfied that he knew the answer; he went up to the guard. The guard said ten. The man said five, but he was not let into the night club. What should the man should've said, and why?

Answer to last riddle ….. it was daytime. After this riddle I am taking a long break from writing. So sorry if anyone misses me.