During the sixteenth century, a relevant number of books related to practical arithmetic were published in Spain. This paper presents a comparative study that aims to identify the object and target of five old mathematics books and the main contents of these books. In order to do so, all the contents and all the examples found in five arithmetic books written during the first half of the 16th century were identified and categorised. A historical-mathematical analysis using a content analysis technique was then applied. The results show the authors' concerns about mathematics at the time and the different contents that were included in some arithmetic books of this century.