Please provide detailed explanation , where do you get each number used for every calculation.

On January 1, 2018, Gridley Corporation had 375,000 shares of its $2 par value common stock outstanding. On March 1, Gridley sold an additional 750,000 shares on the open market at $20 per share. Gridley issued a 20% stock dividend on May 1. On August 1, Gridley purchased 420,000 shares and immediately retired the stock. On November 1, 600,000 shares were sold for $25 per share. What is the weighted average number of shares outstanding for 2018? a. 1,530,000 b. 1,125,000 c. 716,665 d. 516,666