|Definition:|| any real or complex number for which the product by itself is equal to a given real or complex number|
Note 1 to entry: Every non-zero real or complex number has two square roots, each being the negative of the other. For a non-negative real number a, the non-negative square root is denoted by or . For a negative real number a, the number is positive and the two square roots are imaginary numbers, conjugate of each others, denoted by and . For a complex number , the two square roots are and .
Note 2 to entry: The concept of square root may be applied to scalar quantities.