Caboche’s creativity

The most obvious answer to a problem may be good, but it may not be the only one!

This is the Friday recitation. Mr. Mansa asks his students:

Which of the following numbers is not in the series?
2, 4, 5, 6, 8

It’s 5, that’s obvious! All the students find the right answer, except for Caboche, who says “I thought about it, but I prefer 4 because…”.

Mr. Mensa is not happy with the answer, so he deprives Caboche of recreation. He asks him to produce a text on the theme “I should have chosen 5”.

At first I thought of 5, because it is the only odd number.

But why not 8? It’s the only one with a completely closed line.

Then I thought of 2, replacing it by 7, we would have a nice sequence 4,5,6,7,8…

I looked at 6, but nothing came up. I turned it over and over in my head, then… Eureka! By turning the 6 over you get a different number. Nothing like that with the others.

Finally, I considered the 4. The 4 is the only number drawn with 2 lines. It is the only one without any curve. It is square. The others are not. It is also my favorite number: April 4 (it is the 4th month) is my birthday. For all these reasons, I…