it sounds *very* logical: "three" is a noun/object here, and as objects, "three"-s are definitely not countable -- how many different "three"-s you can come up with? paul stregevsky mentioned a very good rule to see if this is a "mass" noun -- can you put "a" before it? "a three"? -- from which sixpack? :)
best, mishka > Mathematically, however, we always say "three is > less than five"; the symbol "<" is called "less > than". Interesting that when we actually compare > numbers we use the amount word, not the number word.
