A farmer sold a few chickens to four different customers on a particular day. It was such that each customer purchased half of the remaining chickens and a half chicken more.

Can you find out how many chicken were sold by the farmer on that day if we tell you that the fourth customer bought a single chicken ?

A total of 15 chickens were sold by the farmer.

We know that the fourth customer bought just one from the total chickens. Thus, we can form the equation:
Total - (Total / 2 + 1/2) = 1
If you solve it, you will find that the total is 3.

Now, we can keep working this method till we reach the first customer.

The 1st customer bought 15 / 2 + 1/2 = 8 (leaving 7)
The 2nd customer bought 7 / 2 + 1/2 = 4 (leaving 3)
The 3rd customer bought 3 / 2 + 1/2 = 2 (leaving 1)
The 4th customer bought 1 / 2 + 1/2 = 1

When we add the numbers, we get
8 + 4 + 2 + 1 = 15.