@core578
Yamada Nishiki (山田錦) is the most commonly grown variety of sake rice, hence the 'King of Sake Rice' (酒米の王) nickname.
Gohyakumangoku (五百万石) is the second most popular variety of sake rice.
五百万石 is actually 'Five Million Stones/Rocks', not 'five hundred million'
五百/go-hyaku = five hundred
万/man = 10,000 (a unit of counting)
石/goku = stone/rock
5x100x10000 = 5,000,000