A positive integer n is said to be good if there exists a perfect square whose sum of digits in base 10 is equal to n. For instance, 13 is good because (7^2)=49 and 4+9=13. How many good numbers are among 1, 2, 3, …, 2007? I have started to make a list of all square numbers and adding their digits in an excel file. ... Until now, I have got good numbers as 1, 4, 7, 9, 10, 13, 16, 19. But, this method takes very long. ... Is there a shorter and smarter way to solve this problem. Login To add answer/comment