Estimate the number of flags hoisted on 76th Republic Day of India.

I will begin by paraphrasing the question prompt. Next, I will clarify if hosting a flag means hosting a full size flag and not a small plastic flag. 

Next, I will talk about the two approaches possible:

Supply Side - Track sale of flags from retailers & distributors 

Demand Side - Track consumption pattern of citizens and institutions

I will go with the demand side analysis. My tree structure looks something like this:

Population - ~140 Cr (30% Urban ; 70% Rural)

Flags are hoisted homes, government buildings, and in commercial establishments (urban context). In Rural -> Homes & Government buildings. 

Key assumptions - 

• Urban & Rural -> 30% & 70% 
• # house holds in urban -> population/4
• # house holds in rural -> population/6
• Government buildings (urban & rural) -> 1 per 1 Lk population
• Commercial establishments -> 10 per 1 Lk (urban only)
• 30% urban homes & 70% rural homes host flags
• 100% govt & 100% commercial establishments host flag