What Does the 'Split' Function Do in Google's Go Language Tutorial?

[d3mm]

So I decided today I wanted to learn a new programming language (for fun).

Normally I would ask this on a general purpose programming site, but I figured perhaps this might be a better place for algorithms of this type?

In the tutorial for Google's "Go" language I came across this, and I am wondering if it's an algorithm for doing something, or if it's just arbitary?

def split (n):
    x = n * 4 // 9  # integer division
    y = n - x
    return x, y

>>> split (17)
(7, 10)
>>> split (56)
(24, 32)

(I re-wrote it in Python as the syntax is probably well known here, and very readable. I wasn't sure if he original Go would be as easy for people who haven't seen Go before), but it is here http://tour.golang.org/#9

 

[gsal]

It seems to be intended for splitting integer numbers into two integer numbers where the first is close to (or exactly) 4/9 (four ninths) of the input of the input number and the second is the close to 5/9, i.e., the complement to 1.0

...but you already knew this

 

[d3mm]

Yes but I was wondering if it had mathematical sigificance beyond the obvious! ;-)