Generous to a fault?

So William Hill are offering £50 million if you can predict the correct order of next season’s Premier League. Those odds would seem generous until you work out the chances of getting it right. By my reckoning (I’m very happy to be corrected if I’m wrong) the chances of predicting the correct order is the reciprocal 20 factorial usually shown as 1/20! or 1/(1x2x3x4x5x6x7x8x9x10x11x12x13x14x15x16x17x18x19x20) which is 1/2.432902008177e+18 or 2,432,902,008,177,000,000 to 1. To put that in context, there is more chance of throwing 60 coins in the air and them all coming down heads!