What do 24 walls, 37 walls and 50 walls in architecture mean?

Si Er Wall refers to a wall with a width of 240mm. The width of the current wall brick is generally 1 15mm, and the two bricks together are 230 mm. Add 10mm mortar joint, and one * * is 240mm, so it is called Si Er wall. Sanqi refers to the width of an ordinary standard brick in the horizontal direction and mortar joint, which is called Sanqi wall in engineering.