HP 35s HP 35s scientific calculator - User Guide - Page 177

Summation Values and the Statistics Registers The statistics registers are six unique locations in memory that store the accumulation of the six summation values. Summation Statistics Pressing   gives you access to the contents of the statistics registers: () to recall the number of accumulated data sets. Press to recall the sum of the x-values. Press to recall the sum of the y-values. Press and to recall the sums of the squares and the sum of the products of the x and y - values that are of interest when performing other statistical calculations in addition to those provided by the calculator. If you've entered statistical data, you can see the contents of the statistics registers. Press then use × and Ø to view the statistics registers. Example: Viewing the Statistics Registers. Use  to store data pairs (1,2) and (3,4) in the statistics registers. Then view the stored statistical values. Keys:   ()   Display: Description: Clears the statistics registers. Stores the first data pair (1,2). Stores the second data pair (3,4).  Displays VAR catalog and views n register. views Σxy register. Statistical Operations 12-11