Category:21x21 arrays
English: This category is for all kinds of things that have 21 rows and 21 columns. For the special case of a matrix see Category:21×21 matrices.
Actual squares (where the sides have the same physical length) containing 441 small squares should be in the subcategory Category:Squares with 441 fields.
Actual squares (where the sides have the same physical length) containing 441 small squares should be in the subcategory Category:Squares with 441 fields.