How many children take the bus to school in world?

There's no definitive answer to how many children take the bus to school worldwide. This kind of data is not centrally collected globally. Information would need to be gathered from countless individual countries and regions, and even then, the accuracy would vary widely due to:

* Data Collection Differences: Different countries have different methods (or lack thereof) for tracking school transportation usage.

* Defining "Bus": The definition of a "school bus" can vary. Does it include minibuses, vans used for school transport, or public transit buses?

* Rural vs. Urban Differences: Bus usage differs dramatically based on geographic location and population density.

* Accessibility and Affordability: Access to school bus services varies greatly depending on income levels and infrastructure.

While a precise number is impossible to obtain, it's safe to say that it is a very large number, likely in the hundreds of millions, considering the global population of school-aged children.