Here's the solution to the puzzle of March:

 The point is that you need to arrive at a situation where "either the fake coin is lighter and is one of these coins; or the fake coin is heavier and is one of those coins".

The first weigh is: 4 vs 4

We will consider 2 cases:

A) the left side is heavier than the right side
B) the two sides are of the same weight

for A) the fake coin is on the scale, that means the remaining coins are all real, for ease of explanation we name the coins as follows:

H1, H2,...

Continue reading ...