The authors define "basic skills" conceptually as the skills necessary for effective participation in modern economies. They base the measure on mastery of at least the most basic level of the Programme for International Student Assessment (PISA), i.e. PISA Level 1.1 skills. That is: Level 1 students can perform basic calculations and understand simple mathematical concepts. They can solve problems involving whole numbers, often requiring only one step or direct application of a formula or procedure. For example, they may be able to identify a simple fraction or measure the length of an object. Level 1 students can extract simple information from texts and follow simple instructions. Level 1 students can demonstrate basic scientific knowledge and understanding of known phenomena. For example, they may be able to name the parts of a plant or understand that heat causes things to expand. The article analyzes gaps in basic skills in young people around the world. The results show that at least two-thirds of young people do not reach the level of basic skills, and the economic loss from this is more than $700 trillion.