The Chinese like the concept of pairs because they believe in "Good things come in pairs".
二 means everything is in pairs.
For example, the symbol “囍”（shuāng xǐ, double happiness）is formed by joining two 喜（xǐ, happiness). It's commonly used during weddings to wish new married couples happy for their future life.
六 means everything goes well.
八 sounds like the word that means “rich”.
九 is an lucky number in Chinese because it means things lasting forever.
__Most of the people like choosing the lucky numbers for their phone numbers, licence plate and door numbers.
The number sì 四(number four) is generally regarded to be a unlucky number as it has a similar sound is the word sǐ 死 （death）, even they got different tones.
Many people would avoid to have 四number four in the lift, for the phone number or car plates.
But the same as the foreign countries, not everyone believe in number 13 is the unlucky number, not all the Chinese people believe in this suspicious as well.