numerator (n.)

1540s, "word or figure by which the number of something is denoted" (a sense now obsolete), from Late Latin numerator "counter, numberer," agent noun from numerat-, past-participle stem of numerare "to count, number," from numerus "a number" (see number (n.)). From 1570s as "the number written above the line in a fraction," by 1670s as "one who or that which numbers."