Dunbar Company had 400,000 shares of common stock outstanding during the year 2013. In addition, at December 31, 2013, 60,000 shares were issuable upon exercise of executive stock options which require a $40 cash payment upon exercise (options granted in 2011). The average market price during 2013 was $50. Compute the number of shares to be used for 2013.

Answer is: 500,000+90,000-(2400,000/50)=542,000

Why assumed shares is 90,000 not 60,000?