Boldmethod’s “Easy Mental Math For Pilots” is an instructional article about using simple arithmetic to support cockpit planning. The supplied article text introduces the subject broadly, while search-result excerpts provide a specific example: using a 60-to-1 relationship between flight-path angle, distance, and altitude loss to estimate a descent. The example says a three-degree descent over three miles yields about 900 feet of altitude loss. The article is educational rather than event-driven; no flight, aircraft, operator, airport, safety occurrence, or regulatory action is identified.