I might continue this tonioght. I got a bonus today so need to invest it somewhere sensible.
its exactly what they want you to do, buy shit loads, thinking you can beat a system that you can't... if you bought ALL the tickets you still wouldn't make a profit as something like 30% goes to charity - if you bought 10 million tickets, and after you got all that silver shit out from under you fingernails, you'd be lucky to come away with a 3 million loss...
assuming the "1/5 chance of winning" written on the back means you need to buy 5 to stand a reasonable chance of getting a win on one card, then if you buy 50, you expect 10 to win (does that agree with what you observed ?).
You can then estimate your chance of making a profit if you know the distribution of winning cards. I bet its something like a logarithmic scale where 50% of winning cards = 1pound, 20% = 2pound, 10% = 5 pound, 5% = 10 pound, 2% = 20 pound etc...
To make a profit, you need each of those 10 winning cards to be worth more than 5 quid. if the distribution is like that above, then you will win more than 5 quid a further 20% of the time (20% =100% - (50%+20%+10%)).
So I reckon, if you buy 50 cards, the chance that your 10 winning cards all bring you more than 5 quid each is 1/0.2^10.... which is a little bit better than one in 10 million ...
probably you are better off just buying one, then you have a 50%*20% = 1/10 chance that you will win more than a quid. Of course, the more cards you buy the more likely to win the one big prize, but if 1 million tickets are sold, there is a 1/1million chance of winning it on one ticket. You could buy a thousand tickets and increase your chance linearly, but frankly 1/1,000 and 1/1,000,000 might just as well be the same - in the statistics world we would call these both mathematically equivalent to fuck all, and one of those options would lose you a grand.
basically, scratch cards are not a recommended investment strategy. the best way to get anything out of scratch cards is to be nice to people and hope that your sunny and pleasant disposition will encourage anyone that gets lucky to be nice to you on the unlikely scenario that they win anything. Or rob them.
