http://easycalculation.com/decimal-converter.php
http://www.tonymarston.net/php-mysql/converter.php
http://www.mathsisfun.com/binary-decimal-hexadecimal-converter.html
http://www.statman.info/conversions/hexadecimal.html
http://www.subnetonline.com/pages/converters/hex-to-bin-to-dec.php
http://www.rapidtables.com/convert/number/hex-to-decimal.htm