Given my love for numbers, lately I have started reading a book on where do our senses for numbers come from? Do animals understand numbers? (They do – but not the way we think). Does a child of 2 months understand the difference between 2 and 3? (You will be surprised!!)

Now I am trying to figure out why is it that in most cultures, we write 2 by repeating 1 in some fashion. Same for 3. But when it gets to 4, we go a very different way. And all cultures have uniformly decided to take a fork while representing 4.

The Roman notation is the most unintuitive. After denoting 2 as nothing but two of 1 and 3 as three of 1, to denote 4, first it introduces 5 !!! And then the understanding of subtraction!!

Why did they do that?