I was trying to figure out what the formula is for finding out how to get the: "excess of issue price over stated value" that goes on the "stockholders' equity" on the balance sheet. Could someone please help me.

Common Stock is the Price of the par value of the stock X number of shares sold.

Additional Paid-in Capital is the difference between the Amount of cash received from the sale of stock and the par value of the stock sold.

For example you sell 100 shares of stock for $20. The par value is $5 per share.

Cash will be debited $2,000
Common Stock will be Credited $500
Additional Paid-in Capital will be credited $1,500