The I Ching or Book of Changes is a compilation which records the experience of people in ancient times with luck and divination. In the Book of Changes, each number has some significance: one is the tai-ji or "great supreme," two is the "two rituals," three is for the "three powers," four for the "four directions, "five is for the "five pathways," six stands for the "six realms," seven for the "seven rules of government," eight means the "eight trigrams ,"nine is for the "nine chains," and ten is the "ten depictions."

    We often say "three yang make good fortune" to describe the hope that misfortune will be held at bay and good luck will follow. It is a saying often used at the New Year and symbolizes a new beginning and finds its origins in the Book of Changes. Yang is the positive force in the universe, and there is enormous yang and very weak yin (negative force) in the first, second, and third of the nine trigrams. So the three yang are very positive.

    Li Heng-li, chairman of the International Taoism Scholarly Foundation, who feels that numbers have no connection with fortune good or ill,  says that the only significance numbers have is what people ascribe to them. Trying to say that a given number is either auspicious or ominous is mere superstition.

    Still, unlike the Western sensitivity to the number 13, Chinese have a whole philosophy built up around numbers, which is spread or experienced in real life.

    Gods can be alone, but people cannot: One is the number marking the beginning, and also has the meaning of "independent" or "alone."

    Tong Feng-wan, a professor of theology at Taiwan Theological Seminary, points out that in Taiwan people prefer even numbers which symbolize "fortune comes in pairs." They are more wary of one, three, five, seven, and nine. Because the character for "odd" in Chinese (dan) also means "alone," people are not very fond of it. But although people like even numbers, the gods can be alone. Thus in odd-numbered months holidays have been stipulated to help people get by, from New Years (first day of the first month on the lunar calendar) and Tomb Sweeping Day (third day of the third month) to Dragon Boat Festival (fifth of the fifth), Chinese Valentine's Day (seventh of the seventh), and Old People's Day (ninth day of the ninth month in the lunar calendar).

    At weddings, when Chinese people give "red envelopes" with gifts of cash, they only send even amounts, like 1 200 or 3 600. Because the pronunciation of "four" is close to that of "death" in Taiwanese, if you send 4 400 to the bride and groom, people won't be grateful and might even criticize you behind your back for failing to understand basic manners. At funerals, on the other hand, people usually give offerings with the last digit being odd, so as to avoid ill fortune not coming "alone."

    Happiness comes in pairs: In the book Popular Chinese Customs Professor Lou zhu-kuang notes that when people got married in ancient times, betrothal gifts would include a document recording all the details of the accompanying gifts. The writing style was rather meticulous. Thus, for example, chickens or ducks would be written as "Four wings of poultry." Gold bracelets would be written "Gold bracelets becoming a pair." Candles would be written as "Festive candles with double glow." No place would odd numbers be allowed.

    When inquiring into the other's name and the "eight character horoscope" of the other party, it would be written for instance: "The groom (or bride) is in the beginning of the sixth month of his (or her) twentieth year, having been born at such-and-such an hour..." The number of characters in the Chinese text would always have to add up to an even number； if they were short one then an "auspicious" character would be added.

    The writer Xiao Min adds that because the character for "odd" also means "incomplete," when she was in her old home in Beijing, they would always make sure that the number of steamed rolls made for New Year's was even in order to make a good beginning.

    Huang Bo-he, a scholar of folk traditions, argues that Chinese have always been rather inclined to the number three. Just open up a Chinese dictionary and there are sayings using three or multiples thereof sprinkled everywhere. They are even more numerous in local sayings and slang.

    He points out that one reason Chinese like three is that it stands for "many." In Lao Tzu it is said that "Tao gave birth to the one, the one gave birth to the two, two gave birth to three, and three gave birth to ten thousand things." From nothing to something, or something to infinity, "three" plays a critical role.

    Elevators without fourth floors: The scholar Su Xue-lin has written that in ancient China the numbers four and 72 were perhaps both mysterious numbers, and moreover that "four" was a symbol for the great earth.

    But in Taiwan four is not especially well looked-upon. Hospitals and hotels normally have no fourth floor, and the numbers in the elevator just skip right from three to five. It's probably only in places where Chinese people live that this type of facility is necessary. Also, the price of an apartment on the fourth floor is usually cheaper.

    In general, Chinese assign little good or bad significance to "five."

    "May the five fortunes approach your door" is a saying often seen at festive occasions. The five fortunes are long life, wealth, health, an ethical life, and a peaceful death.

    Besides this, the five elements (metal, wood, water, fire, earth) provided a framework for people at former times to classify natural phenomena. Confucianism also says that five implies the concept of "the mean."

    The writer on geomancy Zhen-zui points out that Confucians believe that five is very close to the path of the golden mean of "adopting the middle between two extremes," and also promotes the thought of the "five pathways." As a number, five has two at the front and two behind, with one in the middle. "This middle figure has two assistants on each side, and is unbiased in the middle. Thus five fits in well with the idea of the ‘mean’ always promoted by Confucian scholars," he has written.