I know 20, wait, 2 languages

English, Hindi, Bengali the same as you, Urdu (including reading and writing) as well. That apart, I have basic conversation skills in German and Spanish and can manage my way in any country where these are spoken. My latest venture is Russian, which is at a very preliminary stage now but I hope to get to the level of basic conversation in another four to six months (Я хочу говорите по-русски). As for understanding a fair bit, that goes for Gujarati, Marathi, Odia, Assamese and Nepali, mainly because of their resemblance to either Hindi or Bengali.

@ Sraboni

I am impressed by people who know even "just" two languages really well - (regardless of whether these are say English and French or Bengali and Hindi).

When, on the other hand, someone says they "speak" multiple languages, as many sometimes as ten, twelve or fifteen (!) then I know they're lying.

@Guyomar Mother tongue for us, Indians, means the language of the family.

In India, every state has it's own native language. We are originally from the state of Bengal in India. So people belonging to that state spoke in Bengali and likewise, every state had a different language to begin with.

Over hundreds of years as people started moving from one city to another due to jobs, families started relocating and so every state now has people from different states (for us different communities). We live in Jharkhand now whose state/community/native language is Hindi. So the native language of the state is Hindi.

That's a tough call, Guyomar. Practically they aren't any different but I suppose mother tongue is the language you learn on your mother's lap - quite literally. Native can be what you acquire later at a proficiency level that's similar or maybe even better than your (technical) mother tongue. This isn't a linguistic definition, just my personal one.