About RPN history

[salvomic]

Strange... I saw Help for and() but it ...doesn't help much.
In Textbook Ans(n) returns the nth line (stack).
In CAS Ans(n) applies n to an expression in stack 1: i.e.
2. 456
1. x^2
INPUT Ans(4)
returns 16.

In RPN, as you said, Ans(1) returns stack 3. ???