21Vi Hart
In 2012, a mathematician named Vi Hart sent an open letter to Nickelodeon proving Spongebob's Pineapple was geometrically impossible. Pineapple designer Kenny Pittenger responded on his blog (in video description) by posting a new "mathematically correct" design. This new design is now used on the show.
228675309
8675309 is the fourth most common 7-digit password, number one, of course, is 1234567.
23Narcissistic number
A Narcissistic number is a number that is the sum of its own digits each raised to the power of the number of digits.
24Vinculum
The line between the 2 numbers in a fraction is called the Vinculum.
25Fry Lewis Richardson
A mathematician named Fry Lewis Richardson discovered that it is impossible to measure the length of coastlines in a meaningful manner. This so-called Coastline Paradox later led to the creation of the field of Fractal Geometry.
26Ada Lovelace
A female English mathematician named Ada Lovelace wrote an algorithm in the mid-1800s designed to be carried out by a machine. As a result, she is often regarded as the first computer programmer.
27Integral symbol
The integral symbol (∫) used in math is based on the long S symbol because Leibniz thought of the integral as an infinite sum of infinitesimal summands.
