Yep. I just checked with http://www.usinflationcalculator.com/ http://www.usinflationcalculator.com/. That site has a calculator that comes up with almost the

Yep. I just checked with http://www.usinflationcalculator.com/ http://www.usinflationcalculator.com/. That site has a calculator that comes up with almost the exact same conclusion as you. Or, you could assume an average rate of inflation and calculate this using the rule of 72. I like to keep that formula in my pocket for things like this.