The analysis of the achievement of 206 colombian children, spanish speakers, of 1o, 2o and 3o grade of primary school, to read arabic numerals with different structures, shows the tendency to compose correctly the read numeral or to segment the chains of arabic digits using two strategies mainly: implicit segmentation with partial production and explicit segmentation with total production. The children tend to segment the arabic numeral in powerful significant units that already dominate as the groups of ten, for example, ‘thirtyfive, twenty-four’ for ‘3524’. The partial production or total of segments affects the syntax of the verbal expression. The usual evolution of the process of transcodification is relatively independent of the structure of the read numerals. The success through the grades does not present a gradual evolution. In 2o grade descends the correct production and there is great variability in the strategies utilized probably as effect of the progressive incorporation of the rules of the numeration system.