What's the difference between i.e. and e.g.?
1540s, 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.)).
In mathematics, the number that appears on the top of a fraction. In the fraction 2/3, the numerator is 2. (Compare denominator.)