Kind of right, except his odds improved to 50 out of 292,000,050, assuming prior to his buying of the 50, there were 292,000,000 tickets. Simplified his odds of winning are 3.4246569E-7%, as opposed to buying one ticket (1:292,000,001) being 3.4246575E-7%. So in fact, his chances of winning just got worse...I think.