Earn.nu -- How to earn more in earn.nu

The most interesting feature of earn.nu PTC is renting of referrals with account balance.This feature allows us to earn more if we do it in a tricky way.
Suppose that you have started clicking ads today in earn.nu.
Then after 4 days your balance will be 0.4$ ( Approx ).So you can rent a referral after 4 days of your sign up.If that rented referral also do 10 clicks a day ,then you can another 2 referrals after another 4 days.Like this the referral count will be doubled for every 4 days.
In this process we are not investing even a single cent.So follow this procedure and earn more.