Why is the great wall of china important?

The purpose of building The Great Wall of China was to protect northern regions of the country and prevent the invasion of the nomads. This event refers to the 3rd century BC, when the first emperor of China Qin Shi Huangdi united 7 parts of China by putting an end of Warring States period. He ordered to build a big wall with lots of traps in order to create an obstacle for enemies and set clear boundaries of the conquered state.

I’m pretty sure it’s 4, you can check on the calculator

Ais 190 b is 200c it can't be more then 100%