Using Previous Results

In doing calculations, you will often need to use previous results that you have got. In the Wolfram Language, % always stands for your last result.

%the last result generated
%%the nexttolast result
%%% (k times)the kNull previous result
%nthe result on output line Out[n] (to be used with care)

Ways to refer to your previous results.

Here is the first result:
Click for copyable input
This adds 1 to the last result:
Click for copyable input
This uses both the last result, and the result before that:
Click for copyable input

You will have noticed that all the input and output lines in the Wolfram Language are numbered. You can use these numbers to refer to previous results.

This adds the results on lines 2 and 3 above:
Click for copyable input

If you use a textbased interface to the Wolfram System, then successive input and output lines will always appear in order. However, if you use a notebook interface to the Wolfram System, as discussed in "Notebook Interfaces", then successive input and output lines need not appear in order. You can for example "scroll back" and insert your next calculation wherever you want in the notebook. You should realize that % is always defined to be the last result that the Wolfram Language generated. This may or may not be the result that appears immediately above your present position in the notebook. With a notebook interface, the only way to tell when a particular result was generated is to look at the Out[n] label that it has. Because you can insert and delete anywhere in a notebook, the textual ordering of results in a notebook need have no relation to the order in which the results were generated.