n or Out[
] is a global object that is assigned to be the value produced on the n
% gives the last result generated.
%% gives the result before last. %% ... % (k times) gives the k
] is equivalent to %.
] is equivalent to %% ... % (k times).
See the Mathematica book: Section 1.2.1, Section 1.3.3, Section 1.3.4, Section 2.13.1.
See also: In, $Line, $HistoryLength, MessageList.
Here is an expression.
This gives the output of the previous expression.