Problem: what is the sum of natural numbers between 60 and 100
Rationale: "a = first number l = last number sn = n / 2 [ a + l ] between 60 and 100 numbers = 41 = > 100 - 60 = 40 + 1 = 41 sn = 41 / 2 ã — 160 = 41 ã — 80 = 3280 answer : e"
annotated_formula: add(100, const_1)