Summation, suggested reference to Sum

Your etymology of Summation ought to reference the entry on Sum, which clarifies the fact that the root of the “sum” in Summation is “summa”, Latin for the top or highest, which resulted from the Roman practice of adding a column of numbers from the bottom up and writing the addend on top, ergo “summa”, ergo Summation, “ergo sum”, which I found delightful.