Hence, another requirement from the 40 items chosen for the Numeracy scale is that they can be divided into two blocks that reflect the difficulty level and the facet coverage of the entire scale, for psychometric as well as for "face validity" reasons. Subsequently, two 20-item blocks were created which are well balanced with respect to the means of the IRT indicators of discrimination (Mean Rbiserial) and difficulty (Mean b), and in terms of the number of items in each block that represent the five content areas listed in the conceptual framework of numeracy facets, as shown in Table 6 and Table 7, respectively. Thus, the two blocks that make up the Numeracy scale overall satisfy the requirement for psychometric equivalency and each of them represents the richness of the full construct.