High Numbers and Low Numbers
In Japan for high numbers we use a unit of four figures. We indicate the numbers with the unit's names as 1-oku, 10-oku, 100-oku, 1,000-oku and 1-cho. When a number is greater than 1-man, it gets the next unit's name. For example, 1-man times 1-oku is not 1-manoku but 1-cho.
This system of units was introduced from China, and Mitsuyoshi Yoshida transformed this system into a four-figure unit. In those days the Chinese had many systems of units.
For low numbers we use the decimal system. We have a name for every decimal place.
Numbers Which are lower than one begin with "bu". So three-tenth is 3-bu.
We can see some examples of it in idiomatic expressions like: "It's a 5-bu and 5-bu match." or "Share in 4-bu and 6-bu." You catch on to what these expressions mean, don't you?