The square of a positive number is 2000% greater than the number itself, then the square of that number is :

$$\eqalign{ & {\text{Let the positive number be x}}. \cr & {\text{According}}\,{\text{to}}\,{\text{the}}\,{\text{question}}, \cr & x \times x = x + \frac{{\left( {x \times 2000} \right)}}{{100}} \cr & {x^2} = x + 20x \cr & {x^2} - 21x = 0 \cr & {\text{Either}}, \cr & x = 0,\,\,or \cr & x = 21 \cr & {\text{21}}\,{\text{is}}\,{\text{the}}\,{\text{possible}}\,{\text{value}}{\text{.}} \cr & {\text{Then}}\,{\text{square}}\,{\text{of}}\,21\,{\text{is}}\,441 \cr} $$