Among the numerous cuneiform documents available, only two tablets have the characteristics of those presented here; they were written more than forty centuries ago in South Mesopotamia. On one side, they bear the drawing of a field, whose shape is quite complex: the core is divided into rectangles to allow the calculation of the area. Each rectangle bears two inscriptions related to the area. The cadastral sketch inscribed on the first of these tablets is made up of quite regular shapes; the indications on the reverse are legible and are accumulated values of areas that confirm the calculations on the obverse. In 1898, an interpretation of this document based on trial and error was proposed. The other tablet, made up of more intricate geometric shapes, has not been explained until now, the reverse being too damaged to be compared with the indications written on the obverse. The present study takes into account the work done by the surveyor, and suggests a reconstitution of the scribe’s calculations for the two tablets.