On30 is a model railway scale and gauge that represents a narrow-gauge railway system. Specifically, "On30" refers to O scale trains running on a track gauge of 30 inches (762 mm), which is typical for narrow-gauge railroads. In model railroading, O scale generally has a scale ratio of 1:48, meaning that 1 inch in the model represents 48 inches in real life.

"Jack Yang" could refer to various individuals or entities, depending on the context. Without additional details, it's hard to provide a specific answer. Here are a few possibilities: 1. **A Person**: Jack Yang may refer to a specific individual, possibly a public figure, professional, or someone notable in a specific field such as entertainment, business, or sports.

Beverly Berger is not widely recognized in popular culture or historical context, so there may be multiple individuals with that name.

"Coasts" typically refers to the areas where land meets the ocean or sea. These regions are characterized by various geographical features, including beaches, cliffs, dunes, and estuaries. Coasts can also encompass diverse ecosystems such as coral reefs, tidal wetlands, and intertidal zones, which support a wide range of plant and animal life.

A Pillai prime is a type of prime number characterized by its relationship to the factorial function. Specifically, a Pillai prime \( p \) is defined as a prime number for which there exists a positive integer \( n \) such that \( n! \equiv -1 \mod p \). This means that when \( n! \) (the factorial of \( n \)) is divided by the prime \( p \), it leaves a remainder of \( p - 1 \).

A "dummy round" generally refers to a type of ammunition that is used for training, testing, or demonstration purposes but is not intended to be fired. Here are a couple of contexts where the term may be used: 1. **Firearms Training**: In the context of firearms, dummy rounds are inert cartridges that may have the same weight and dimensions as live ammunition but contain no propellant or primer.

A Diophantine equation is a polynomial equation of the form: \[ P(x_1, x_2, \ldots, x_n) = 0 \] where \( P \) is a polynomial with integer coefficients, and the solutions \( (x_1, x_2, \ldots, x_n) \) are required to be integers.