@Peyton ******
it's usually a personal thing. Some big event in their life or some number they think they received from a special divination or something.
If you've ever seen Thais lighting little blocks and then putting them in sand near a shrine, when they finish burning there is a number on it. Then they will go play the lottery with this number.
There's also a cup full of sticks and they shake it and the first ones that fall out they use those numbers etc. They're very superstitious.
Also "lucky number" lottery tickets fetch higher prices and unlucky numbers may be discounted. I think repeating numbers are thought of as lucky but I honestly don't know much. I'm not superstitious so I've never looked into it.