On January 1, 2015, Gridley Corporation had 250,000 shares of its $2 par value common stock outstanding. On March 1, Gridley sold an additional 500,000 shares on the open market at $20 per share. Gridley issued a 20% stock dividend on May 1. On August 1, Gridley purchased 280,000 shares and immediately retired the stock. On November 1, 400,000 shares were sold for $25 per share. What is the weighted-average number of shares outstanding for 2015?