In all three domains, proficiency is estimated on a scale of 0-500 points. The scale is also divided into proficiency levels. In literacy and numeracy, there are five proficiency levels, where level 5 is the highest and level 1 is the lowest. It is possible to have proficiency below level 1. Problem solving in a technology-rich environment has three proficiency levels, and it is also possible to have proficiency below level 1.