Code cracking

If I had a rupee for every time I've been puzzled in India I'd be a very wealthy lad. Here's one example. All across India the walls of residential streets are decorated with speedily drawn chalk calculations. I thought at first they were house numberings. Later I thought they might be file numbers that prove house ownership. Or the calculation of debts. Or redirection notices for people who have moved house. Or the markings of a tax or electricity bill collector. I'm no closer to the answer. But there is a side of me that likes this. Clearly there is a system of sorts for the achievement of a socially useful end about which I have no idea. And thus I have faith that things will happen, even when there is no sign that they will. Invisible processes that I can't see will ensure it. How does India work - it's a secret written in chalk code.