They are regular numbers that you know and love: 1, 0, -5, 4.534343, 232423432.4787865, -0.0000000000002, etc. The imaginary part of a complex number is a real number (like above) multiplied by a unique little number called i.What is i? Plainly said, i is the square root of -1. Plainly said, but that doesn't make any sense. Let's look at square roots. The square root of 4 is 2 because 2 * 2 = 4. The square root of 1 is 1 because 1 * 1 = 1. The square root of 64 is 8 because 8 * 8 = 64. Now then, (what) * (that same what) = -1 ???? Answer: there is no such thing. The what can't be -1 because -1 * -1 does not equal -1; it equals positive 1. Therefore there is no such thing as the square root of negative one.