Rev 13:18 Here is wisdom. Let him that hath understanding count the number of the beast: for it is the number of a man; and his number is Six hundred threescore and six.
Many people have tried to calculate the number of the beast. Using many different methods no one yet has been verifiably been able to calculate the name. Honestly when I hear of people trying to figure the name I kind of chuckle to my self. Look at what the verse says though the writer explicitly encourages them that have understanding to count the number of the beast.
A man by the name of Tim Cohen has been trying to do just that. Author of "Antichrist and a cup of tea". The way he does it is through the Cabalic numbering system.
What is the Cabalic(Gematria) numbering system? It originates from the Old Hebrew way of counting, each letter has a value that can be added up.

So why use this number system? Well the main reason is because the verse says to calculate the number of his name, how else do you calculate a number of someone’s name without using this method? Secondly the actual number is calculated in gematric.
Taken from the Greek in Rev 13:18 for 666.
χξς (refer to the chart above)
chi xi stigma
used as numbers; denoting respectively 600, 60 and 6; 666 as a numeral: - six hundred threescore and six. - Strongs
Heres who Tim Cohen has come up with so far.
P r i n c e 70 90 9 50 3 5
C h a r l e s3 8 1 90 30 5 100
o f 60 6
w a l e s 0 1 30 5 100
In Gematric the total equals 666
Tim Cohen says what Hebrews chiefly call Prince Charles of Wales in the press converted into Hebrew which (3 words not 4) actually converts to 666 as well. As you have probably guessed the probability of this happening is very slim 1 in 10 to the 50 is the estimated probability. That’s a 1 with 50 zeros behind it. Tim states that Prince Charles of Wales is the only person in history to fit this number.
Tim also does a biography on Charles which seems to even further connect Prince Charles to the beast.
Heres a link to his book at Amazon.com
Antichrist and a Cup of Tea (Paperback) 
I have not read it yet but If you are interested investigate. I might get it sometime email me and tell me what you think of it if anyone buys it.
You can watch his video here for free.
http://www.lonelantern.org/cup_of_tea_video.html