>>>>But it's not the same number anymore. It's lost something of its essence, like identity... En, I don't recognize you... Who are you and what have you done with en?
>>>
>>>You've lost me
>>
>>If something "turns a negative number into positive" (see first message in the thread), it's not the same number anymore.
>>
>>A function which would return a positive number of same magnitude as the (possibly negative) argument is fine, it may return a different number.
>>
>>Just a mathematician's peeve - you can't change the value of a number. You can change the value of a variable, you can have a function which would return anything, but even it can't change a number. A number is a constant.
>
>You two are both math savants so maybe one of you can explain something to me. It is i, the square root of negative 1. Dumbo me finally asked a professor about it. I said the square of anything is a positive. He said that's true in theory but i makes possible many theorems. That was when I knew I had no trajectory in advanced mathematics.
>
>Tamar, are you there? You have a PhD in math. Maybe you can explain it to me in terms a layman can understand.

Mike,

people have written books about this number, which we called i in high school. Still you want an easy explanation? http://en.wikipedia.org/wiki/Imaginary_unit