If mathematics is your subject and you love tattoos too then youâll love this one! Incredible Euler’s identity scarification! Eulerâs Identity is one of the most fascinating mathematical equations. Iâm sure you all know that itâs the only equation that shows nine mathematics concepts-1, 0, pi, e, i, addition, multiplication, exponentiation and equality. Donât forget to check out the Euler Identity invisible ink pinned below.