Complex number
Complex numbers can be shown on a so-called complex plane. If you have a number , you can go to point a on the real axis and point b on the imaginary axis, and draw a vector from  to . The length of this vector can be calculated using the Pythagorean theorem, and the angle of this vector is simply the angle between the positive real axis and this vector—going counterclockwise. The length of a vector for a number  is called its modulus or absolute value (written as ), and the angle is called its argument ().