Fortis Easy Math Ref. 7242


Fortis Easy Math is a quirky 70s watch to the bone. The watch has a cushion case, two crowns and a busy dial. The dial has tritium plots, beautiful deep blue color, elevated disc with compass cardinal directions and a rotating slide rule bezel.

The stainless steel case has a beautifully sunburst finish with radially brushed surfaces and polished sides. A similar radial finish was used at the time by Omega in their various references among many others. The watch may look like a dive watch, but it is not and has a very modest depth rating.

Basic Information

Lug to lug44mm
Lug width20mm
MaterialStainless Steel
Water Resistance5 ATM

The Dial and the Bezel

The most interesting aspect of this watch is the dial and the bezel. The bezel can be used perform multiplication and division operations by using the slide rule (and hence the name ‘Easy Math’). There is a lot of information online how to use the slide rule and how to use watch as a compass, so I will omit those.

The Case

The 37mm case is often advertised as 38mm by over eager sales guys to serve the big watch fetish. The case features two crowns, and is thus typically labeled incorrectly as EPSA super compressor. The EPSA super compressors feature a dive helmet and other EPSA markings on the case-back, but the EasyMath is missing those.

Example of EPSA Markings

The upper crown manipulates the internal slide rule bezel. and the lower crown winds the movement and sets time. The internal gear of the slide rule bezel crown is plastic. The same applies to the teeth on the bezel disk. When encountering mechanical resistance, one should probably avoid adjusting. Turning the bezel risks damaging the gear or the teeth. Replacement parts are unavailable.

The Movement

The manual FHF-ST96 movement is not particularly well regarded, but it is sometimes called workhorse movement. It operates at frequency of 18000A/h and has a power reserve of 48h. While it lacks many nice modern features, the only thing it left me yearning for is hack seconds.

The winding experience of the movement is smooth and the hands move precisely when time is set. While the FHF-ST96 is found in many fake / franken watches, I haven’t noticed that the Easymath is being faked. This would be unlikely due to the lack of market for the watches, but it would be a mistake to assume that something is too cheap to fake.


The unusual dial alone makes Fortis Easy Math worth collector’s interest. The movement is not haute horlogerie, but it gets the job done and at least feels nice to wind. Despite the modest technical properties and lack of complications, the watch feels excellent on wrist, looks great on a variety of straps and above all, you can find one for cheap. In the end, what more can you ask for?

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