Johnson Level & Tool Mfg. 40-6004 - Manual (Page 18)

Press and release the button.
Upon pressing the button the LCD screen will be cleared however the
Indirect measurement calculation is stored.
The Indirect measurement mode will remain active on the LCD screen .
Take the second Indirect measurement.
When the Indirect measurement calculation appears in the bottom row
press and release the button again.
You will now see the previous Indirect measurement calculation at the top
row being added to the most recent Indirect measurement calculation in
the middle row.
The sum of both Indirect measurement calculations will be displayed in
the bottom row.
Follow this sequence to continue tallying additional Indirect measurement
dimensions.
To subtract an Indirect measurement simply press and release the
button during the sequence and that value will be deducted from the total.
18 ©2013 Johnson Level & Tool - Rev. 1
6833H-English_Manuals 4/2/13 1:26 PM Page 18