Unfortunately, the most famous number tattoos are those used by the Auschwitz concentration camp to identify prisoners during the Holocaust. Interestingly, these serial number tattoos were not initially done with a normal tattoo machine. Instead, a metal stamp was used. This stamp had a series of interchangeable numbers, each made up of several sharp needles. Once the numbers were set, the stamp was pressed against the skin of the prisoner, usually on their chest. The needles broke the skin and then ink was rubbed into the wound, forcing ink into the layers of the skin and creating a tattoo. Later, concentration camp leaders determined that the tattoo stamp was not very practical and resorted to a single need tattoo method that was more effective and efficient. Interestingly, a prisoner being assigned a serial number and having that number tattooed on their forearm was a good sign, or as good a sign as could be had in that environment. Those prisoners bound for the gas chamber were not tattooed because they were not given a number. A number tattoo meant that, for at least a little while, you were going to live.
Fortunately, number tattoos have come a long way since Auschwitz. Number tattoos are attractive for a variety of reasons. First, they are clean-looking, simple symbols. Arabic numbers, what most people think of when they visualize a number (like 0, 1, 2, 3, 4, 5, etc.), are ideal for tattoo. They can be tattooed in a variety of fonts, from minimalistic to intricate, that will age well, remaining crisp and clear. Mathematical tattoos are mostly done using the Arabic system because standard math is done using Arabic numbers
Number tattoos can also be done in other numerical systems, like Roman, which is a system based off of addition. In Arabic numerals, twenty two is denoted as 22. In Roman numerals, twenty two is designated as XXII, which means 10 (X) + 10 (X) + 1 (I) + 1 (I). Which system is used for tattoo designs is entirely up to individual presence. Oftentimes, date tattoos, like birth dates, are done in Roman numerals.
Numbers also have a long history of symbolism and deeper meaning. In literature and art, including tattoos, numbers are used to represent something beyond a numerical value. Number one (1) is synonymous with first. It is also a symbol for unity. A number one tattoo might mean that we are all one people, we are united despite our differences. Weirdly enough, number one stands for the opposite idea, too. Number one is independent, and individual that stands alone, apart from the rest. Number two (2) is representative of duality or opposing forces. Number two tattoos can illustrate the binary nature of the world, which creates harmony and balance. Light is balanced by darkness, male is countered by female, and good is contrasted with bad. This is a very important theory all over the world and is found in many different cultures. Three (3) is perhaps one of the most religiously significant numbers.
In Christian theology, the one and only God is comprised of three different parts (Father, Son, and Holy Ghost), known as the trinity. A number four (4) tattoo symbolized order and the universe. There are four elements (earth, fire, wind, water), four true directions (north, south, east, west), four seasons (Spring, Summer, Autumn, Winter), four ages of man (childhood, youth, middle age, old age), four phases of the Moon (new, half waxing full, half waning), and four bodily humors (blood, choler, bile, and phlegm). Obviously, some of this symbolism is due to human organization and categorization, but it is no less valid.
There is a list of such symbolism for most numbers, but there are certain numbers in tattooing that are more significant, and more popular, than others. Seven (7) is a common choice for tattoo designs. Religiously, seven is thought to be the perfect number. In Biblical circles, it is called the Divine number, symbolizing constancy and wisdom. Throughout the Bible, rituals were performed seven times, purification was done seven times, and the world was created in seven days. In other cultures, seven was also considered significant or even lucky. There are seven days in the week, seven mythological graces, seven deadly sins, seven seas, seven natural wonders of the world, and seven wonders of the Middle Ages. Seven is considered by many people to be a lucky number.
The other popular number tattoo is of the number thirteen (13). This is a seemingly weird tattoo choice because superstitious people consider the number thirteen to be unlucky (Fear of the number 13 is called triskaidekaphobia). Friday the 13th is an especially unlucky day and hotels often designate the 13th floor and room to be 12b, so as to avoid any unhappy guests. However, number thirteen tattoos are considered to be symbols of good luck.
For a variety of reasons, some personal and some widely known, the body art community embraces the traditionally unlucky number as a good lucky charm. Some people believe that the body modification group is drawn to the avoided number because lots of people fear it, so it gets pushed out and ostracized. A fringe number is the ideal symbol for a fringe society. Perhaps, over time, the body mod community will warp the customary view of the number thirteen and make others believe that it is a good number, too.