
Determines whether an input is a number or list.
Ans - the number or list to examine
Ans - 1 if the input is a number, 0 if it is a list
A [,∟A if input is a string]
TI-83/84/+/SE
Deep Thought
:For(A,465230.61649186,465230.61649186
:Ans->A
:A=Ans(1
You can replace 465230.61649186 with any obscure and nearly impossible number.
If Ans is a list, it is stored to ∟A. A remains whatever that number is, and A=Ans(1 (assuming that Ans as a list has at least one value) returns false. If Ans is a number, it is stored into A, thus A=Ans(1 (Ans times 1) returns true.
The For( command is used to avoid updating Ans. End should be added to the end if this routine is used inside a larger program.