structural:expansion, information:highlighting, structural:scholar_edition, stylistic:style_transfer
Imaginary integers and imaginary numbers

When the imaginary unit is repeatedly added or subtracted, the result is some integer times the imaginary unit, an imaginary integer; any such numbers can be added and the result is also an imaginary integer:

a i + b i = (a + b) i. {\displaystyle ai+bi=(a+b)i.}

Thus, the imaginary unit is the generator of a group under addition, specifically an infinite cyclic group.

The imaginary unit can also be multiplied by any arbitrary real number to form an imaginary number. These numbers can be pictured on a number line, the imaginary axis, which as part of the complex plane is typically drawn with a vertical orientation, perpendicular to the real axis which is drawn horizontally.