+8581 "i" and sometimes you'll see "j" stand for imaginary numbers, or mathematical constructs created by mathematicians in order to make certain kinds of equations work out right. Imaginary numbers are part of something called Complex Numbers. Not complex in the sense that they are difficult to solve, but complex in the sense that they are made up of two parts -- a real number (integers, for example) and an imaginary part. For example: 23 + i10 means the integer 23 plus an imaginary component, i10.
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