The absolute value is defined for real and complex numbers. For real numbers, the absolute value coincides with the number itself if the latter is either positive or zero. The absolute value of a negative number is obtained by multiplying the number by -1, i.e. by changing its sign. The absolute value if a number r is denoted |r|. Therefore, |r|=r for r0 and |r|=-r for negative r. In other words, |r| is the distance form number r to the origin. In this form, the definition applies to complex numbers that are identified with points in the plane.