So, you want to know how many people in India use WhatsApp daily? That's a classic product management interview question! It's all about showcasing your problem-solving skills and ability to make data-driven estimates.

Now, we don't have access to WhatsApp's internal data (wouldn't that be nice!). But we can use publicly available information and a structured approach to get a pretty good estimate. Here's how I'd tackle this:

1. Define the Scope & Key Metrics

First things first, let's be clear about what we're measuring. We're interested in:

• Daily Active Users (DAU): Unique users who open WhatsApp at least once in a 24-hour period in India.

• India Focus: We'll need data specific to India, not global WhatsApp usage.

2. Break Down the Problem

Instead of directly estimating DAU, let's break it down into smaller, more manageable pieces. We can use a top-down approach:

• Total Population of India: Let's start with the overall potential market size.

• Smartphone Penetration: Not everyone in India owns a smartphone, so this is a crucial filter.

• WhatsApp Market Share: Of those with smartphones, what percentage use WhatsApp?

• Daily Active User Rate: Finally, what percentage of WhatsApp users in India are active daily?