That number is called "i", the imaginary unit. The name "imaginary" is for historical reasons; these numbers have many practical applications, for example in electricity.
There are mathematical concepts that mathematicians call "imaginary numbers" these are a multiple of the square root of minus 1. Infinity is not a real number either.
Because as a prime number it is very boring.
Pringles
Mathematicians decided that, since the square root of a negative number does not exist, they would use the first letter of "imaginary" to represent this "value".
Two, multiplied by the square root of negative one. (2i) The square root of negative 1 is purely imaginary, but mathematicians don't have much else to be imaginative about.
Yes
10 mathematicians.
1 is not a prime number because it can be evenly divided by itself and by 1, the opposite as per the definition of a prime number.
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You can also call that 1 square cm, if you wish.
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