1089 is the integer after 1088 and before 1090. It is a square number, a nonagonal number, a 32-gonal number, a 364-gonal number, a centered octagonal number. 1089 is the first reverse-divisible number. The next is 2178, they are the only four-digit numbers that divide their reverse. 1089 is used in magic tricks because it can be "produced" from any two three-digit numbers. This allows it to be used as the basis for a Magician's Choice. For instance, one variation of the book test starts by having the spectator choose any two suitable numbers and apply some basic math to produce a single four-digit number; that number is always 1089. The spectator is asked to turn to page 108 of a book and read the 9th word, which the magician has memorized. To the audience it looks like the number is random, but through manipulation, the result is always the same, it is this property that led University of Oxford mathematician David Acheson to title his 2010 book'1089 and all that: a journey into mathematics'. In base 10, the following steps always yield 1089: Take any three-digit number where the first and last digits differ by 1 or more.

Reverse the digits, subtract the smaller from the larger one. Add to this result the number produced by reversing its digits. For example, if the spectator chooses 237: 732 − 237 = 495 495 + 594 = 1089 The spectator's 3-digit number can be written as 100 × A + 10 × B + 1 × C, its reversal as 100 × C + 10 × B + 1 × A, where 1 ≤ A ≤ 9, 0 ≤ B ≤ 9 and 1 ≤ C ≤ 9, their difference is 99 ×. Note that if A − C is 0, the difference is 0, we do not get a 3-digit number for the next step. If A − C is 1, the difference is 99. Using a leading 0 gives us a 3-digit number for the next step. 99 × can be written as 99 × + 99 = 100 × − 1 × + 90 + 9 = 100 × + 90 + 9 − + 1 = 100 × + 10 × 9 + 1 ×. Its reversal is 100 × + 10 × 9 + 1 ×; the sum is thus 101 × + 20 × 9 + 101 × = 101 × + 20 × 9 = 101 × + 180 = 1089. Multiplying the number 1089 by the integers from 1 to 9 produces a pattern: multipliers adding up to 10 give products that are the digit reversals of each other: 1 × 1089 = 1089 ↔ 9 × 1089 = 9801 2 × 1089 = 2178 ↔ 8 × 1089 = 8712 3 × 1089 = 3267 ↔ 7 × 1089 = 7623 4 × 1089 = 4356 ↔ 6 × 1089 = 6534 5 × 1089 = 5445 ↔ 5 × 1089 = 5445Also note the patterns within each column: 1 × 1089 = 1089 2 × 1089 = 2178 3 × 1089 = 3267 4 × 1089 = 4356 5 × 1089 = 5445 6 × 1089 = 6534 7 × 1089 = 7623 8 × 1089 = 8712 9 × 1089 = 9801Numbers formed analogously in other bases, e.g. octal 1067 or hexadecimal 10EF have these properties.

The numerical value of the cosmic microwave background radiation redshift is about z = 1089 In the Rich Text Format, the language code 1089 indicates the text is in Swahili

Kopino, or Korinoy in Filipino slang, is a child of mixed Korean and Filipino descent. A Filipino delegate at the 2005 international conference of ECPAT called for an investigation into the proliferation of Kopinos. According to the delegate, when the Korean fathers return to Korea, most of them stop contacting their children in the Philippines and no longer provide any form of support; the responsibility falls on the Filipina mother who has to raise the child herself. The Philippines is a strong Catholic Nation. Abortion is Criminal and Contraceptives is not discussed; the Kopinos are left to be supported by their Mothers. This problem occurs by a wrong sex-culture of Korean men. Korean men go to the Philippines for language training or sex tourism without taking responsibilities; as their fathers are not married to their mothers, the children are unable to obtain South Korean citizenship. As as 2003 they were believed to number fewer than 1,000; as a result, Filipinos' perception of Korean men has taken a turn for the worse.

In response, South Korean NGOs such as the Daejeon Migrant Workers Support Center, as well as locally established NGOs like the Kopino Children Center, have begun to establish branch offices in the Philippines to provide social services to the children and their mothers. There are Filipino Amerasian and Chinoy/Tsinoy in the Philippines. A 2016 article in The Sungkyun Times said that Kopinos are referred to as the "New Lai Daihan", a 2013 article in The Granite Tower said that Kopinos are considered to be the "second version of Lai Dai Hans". A 2008 article in The Korea Times said that there may have been 10,000 Kopinos in 2008, the 2008 news article said that it was estimated that there were 1,000 Kopinos in 2003. A 2011 article in Sun. Star Cebu said that Yoon Ji-hyun, president of the Kopino Foundation Inc. in Cebu, said that most Kopinos live in Quezon City. A 2016 article in The Sungkyun Times said that "the most important" factor, causing more Kopinos to be fathered by Korean men was that the Korean men were deceiving the Filipino women about their intentions to have a future together with the Filipino women.

The 2016 article said that 90% of the Korean fathers of Kopinos were students who were in their twenties. South Korean television network MBC made a video where they interviewed Filipino hostesses at a hostess bar, located somewhere on the island of Cebu in the Philippines. In the English-language dub by Link TV of the original MBC video, the video's narrator explained that "Most of the Korean men who solicit prostitution don't want to use a condom, causing prostitutes to get pregnant with their babies". In the dubbed video, a Filipino bar hostess was asked the question "Are there many Korean babies?" by an interviewer to which she replied "Almost, Korean men don't use a condom". A 2016 article in The Korea Times said that ECPAT Korea classified the fathers of Kopinos into three broad categories, it said that there were young Korean men in school who went to the Philippines for the purpose of learning English, it said that there were middle-aged Korean men who went to the Philippines for business reasons.

Third, it said that there were Korean men who stayed in the Philippines for a short time for reasons of prostitution. In a 2016 article in The Sungkyun Times, 80% of Filipinos are Catholics, Catholics are discouraged from using artificial contraceptives and abortion; this religious factor of Filipino women contributed to the increase of Kopinos. The article said that 90% of the Filipino mothers of Kopinos who had talked to the We Love Kopino organization were women who worked by teaching English or doing some other type of work that did not involve prostitution; the article said that this high percentage of non-prostitutes was contrary to the idea that the majority of the Filipino mothers of Kopinos were prostitutes. South Korean television network MBC made a video where they interviewed Filipino hostesses at a hostess bar, located somewhere on the island of Cebu in the Philippines. In the English-language dub by Link TV of the original MBC video, the narrator referenced the hostess bar when he said that "Many of the women who work here are Kopino mothers working to support their babies after being abandoned by Korean men," and the narrator said that "The majority of Kopinos are born from hostess bars."

South Korean television network MBC did a video that talked about Korean men soliciting prostitutes in the Philippines. In the English-language dub by Link TV of the original MBC video, the narrator said, "With more and more Koreans visiting the Philippines to study or for vacation, the number of Koreans in the Philippines has increased four times in the last ten years; this has led tourism companies in to create prostitution tours, attracting Korean men." The narrator stopped talking, a "tour guide" whose face was blurred out said, "We have a night tour in our travel course. It costs a hundred dollars for four people." The narrator resumed talking, the narrator said, "Neon signs still shine brightly from the hostess bar for Koreans on Cebu street. About two-hundred and fifty Koreans have been arrested for soliciting prostitution in the Philippines during the last five years, more than any other group of foreigners." The Philippine Government is on crack down for these illegal activities. A 2015 article in Bangor Daily News said that Koreans were embarrassed about the Kopino issue, it said that Koreans felt that not helping Kopinos made Koreans look "dishonest" due to the Kopino issue being similar to the Korean comfort women issue.

In a 2013 article in The Korea Times, an official of a Filipino woman's organization said, "Filipino