There’s absolutely no end to the variety of designs people can get inked on when it comes to tattoos! When it comes to intellectuals, they love to display their intellect; by displaying complex functions, formulas and tedious calculus as tattoo designs. This old guy is perhaps a geometry freak, hence displaying Pi r-square formula on his arm. Well, if you do not know this is the formula that calculates the area of a circle; pi(3.14) multiplied by the square of the radius of the circle. Great way to exhibit your love for maths, isn’t it?