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Ahmad ibn Ibrahim ibn Ali ibn Munim al-Abdari
Ibn Munim from Marrakech used Khayyam’s earlier studies to plot a triangular numerical grid that allowed him to figure permutations and combinations. This exercise yields, for example, the maximum number of words that can be created with the 28 letters of the Arabic alphabet. Four hundred years later, the 17th-century French mathematician Blaise Pascal reinvented Ibn Munim’s numerical grid.