《农桑辑要·栽桑柘附·义桑》
墙内空地总计有一万平方步。每平方步植桑一株，可栽桑一万株，每户可分得桑树五千株。
墙内空地，计一万步，每一步一桑，计一万株；一家计分五千株。
The empty space inside the wall is 100,000 square steps. With one mulberry tree planted every square step, the total will be 10,000 trees, which can be split between the two households with 5,000 trees each.