I'm assuming this is 0.1666666...
Which in that case is 1/6.
(Just from memory)
To do 0.161616161616...
First, assign 0.161616... a variable, say it's x.
Now say 100x, what is it.
16.1616161616...
Now subtract x from 100x.
16.161616161616... - 0.16161616...
Or, 99x
99x = 16 in this case right now
Divide both sides by 99
x = 16/99
So it really depends what's repeating, it's either 1/6 or 16/99.