the numbers are each sake's seimaibuai, pr: say-my-boo-eye, or rice polishing ratio. Degree to which rice is milled before brewing. represent the remaining % of each grain of rice after it has been polished, and are indicative of aroma, flavor, and refinement.

Dassai 50 Junmai Daiginjo  
  Nigori Yamaguchi prefecture $32 720ml 
  slight sweetness, clean, semidry, floral aromas.  

Dassai 23 $85 300ml, $185 720ml 
  premium 80% milled.

Yaegaki Mu $34 720ml, ripe fruit aromas. 
junmai daiginjo
pr: june-MY dye-/g/eenj-yo
    /g/ hard g as in great. 

junmai /pure rice 
  only rice, water, yeast, koji 
  rice is polished to at least 70%.
dai /big 
daiginjo super premium sake 
  rice is polished to at least 50%. 
serve chilled