The development of economic and commercial activities in Mesopotamia during the second millennium BC required the implementation of appropriate administrative and accounting practices. These practices especially concerned the field of numbers and measurements (weight, capacity, length) as scribes had to deal with noting quantities, evaluating losses or profits, book-keeping and business operations. A new reading of several administrative documents, often published in incomplete form, reveals the presence of a specific system of number writing ; a centesimal place value system. This way of writing numbers is similar to the sexagesimal place value system, well known at that time, according to the texts produced in the “school context. This article is aimed at exploring the nature and contexts of use of the centesimal place value system, in order to further enrich the discussion on the classification of the different types of numeration.