Small ruler (~6 inch) with strange markings. Bought a slide rule

The crew of Apollo 13 used a 5-inch, metal slide rule, model N600-ES made by Pickett as a back up on-board computer. It was a model that was popular among engineers, scientists

Woodworking Ruler and Magnetic Torpedo Level :Die cast aluminum limiter, three - sided finish milling surface, fast positioning of multiple angles and fast drawing parallel lines.Torpedo Level with 3 different bubbles for leveling level, plumb and 45 degree. Clear Scale:Laser scale, precise and clear, not easy to wear,Marking hole design, dimension marking and Angle marking are more convenient to use.

Woodworking Ruler 12 inch Metal Measuring Ruler and Torpedo Level Set,Different Bubbles/45°/90°/180°Measuring, T Type Woodwork Adjustable Sliding

Refurbish an Old Slide Rule : 12 Steps - Instructables

Vintage Six Inch Mini Slide Ruler in Case

Small ruler (~6 inch) with strange markings. Bought a slide rule on and this small ruler came with it. I can't figure out its purpose. : r/whatisthisthing

Antique STANLEY 24 FOLDING BOXWOOD RULE No. 6 w/ 12 BRASS SLIDE 19th – Get A Grip & More

vicrays Woodworking Ruler Precision Pocket Rule - 12, 8, 6 inch Metal Slide Stop Marking Ruler Metric inch Measuring Wood Working Scribi

Six inch PICKETT & ECKEL Slide Rule with Original Leather Sheath - 768 – Jim Bode Tools

Midori Compact CL Multi Ruler 30cm Clear (42237006)

Slide rule scale - Wikipedia