Assume your data at B2 looks like this:
94
82
35
92
94
13
37
32
54
37
and you want to sum arbitrary groups of adjacent numbers,
using Pivot Table.
Make a list of arbitrary labels like this:
Group1
Group2
Group3
For each label: Copy > Insert Copied Cell > Shift cells down
A desired grouping might look like this:
Group1
94
82
35
Group2
92
94
13
Group3
37
32
54
37
Pivot Table > Multiple Consolidation Ranges
Ranges:  A1:B4, A5:B8, A9:B13
       (The label and a blank column in front are included)
Layout: Drag Row into COLUMN, Column into ROW
The Pivot Table will look like this:
Sum of Value  Row
Column      (blank)
Group1      211
Group2      199
Group3      160