On January 1, 2021, Imy Corporation had 300,000 common shares outstanding. There are no preferred shares issued. On March 1, Imy issued 45,000 new shares to raise additional capital On July 1, Imy declared and issued a stock split (2 for 1). On October 1, Imy purchased on the open market 180,000 of its own shares ($35 each) and retired them Required: Calculate the weighted average number of common shares outstanding to be used in calculating earnings per share for 2021