Given an integer n, return the n rows of a number square — row i is the number i, repeated n times and separated by single spaces. The nested loopsNested LoopsAn outer loop over rows, an inner loop appending the row number n times, with spaces between repeats. version builds each row number by number. The join/repeatBuild with Join / RepeatDescribing the row directly as "the string i, repeated n times, joined by spaces" — a single expression in most languages. version says exactly that in one expression, skipping the inner loop in every language with that built-in available.