Everyone knows that on high-speed trains (as well as regular trains), one side of the aisle in the second-class carriage has seats for two, while the other side has seats for three. But why is that?
Aside from providing comfortable seating and accommodating more passengers, this arrangement has another benefit: it allows groups of different sizes to sit adjacent to each other without leaving anyone solo.
For instance, a group of four can choose two seats together, while a group of five can choose one row of two seats and one row of three seats, and even a group of eleven can fit into "3+3+3+2" configuration.
When the total number of passengers is even, everyone can sit in pairs, but when it's odd, selecting one row (or any odd number of rows) with three seats makes it even again.
There's actually a mathematical concept hidden within:
If two or more integers have only 1 as their greatest common divisor, they can sum up to any integer greater than a certain value.
With 2 and 3, you can make any positive integer greater than 1.
As for why first-class and premium seats don't follow this pattern, do we even need to ask?
