When going through a portal, the game doesn't divide or multiply the coordinates, and transports the player to the same coordinates, but in another dimension. This affects both Nether and End portals.

Example: A portal in the Overworld with the coordinates (x:800, z: 800), will transport you to the Nether, at (x:800, z:800), not (x:80, z:8) as it should be.