PERCENT - A PRIVILEGED PROPORTION

Why is percent, a ubiquitous mathematical concept, so hard to learn Th is question motivates our review. We argue that asking the question is worthwhile because percent is universal and because it forms a bridge between real-world situations and mathematical concepts of multiplica tive structures. The answer involves explaining the long history of th e percent concept from its early roots in Babylonian, Indian, and Chin ese trading practices and its parallel roots in Greek proportional geo metry to its modem multifaceted meanings. The answer also involves spe cifying what percent is: its meaning (fraction or ratio) and its sense (function or statistic). Finally the answer involves understanding th e privileged language of percent-an extremely concise language that ha s lost its explicit referents, has misleading additive terminology for multiplicative meanings and has multiple uses for the preposition of. The answer leads to speculation in light of previous research, concer ning what can be done to teach percent-and other multiplicative mathem atical concepts-more effectively.