There isn’t a specific font that can be universally considered the most popular for address numbers, as it can vary depending on personal preference, regional conventions, and the overall aesthetic of the neighborhood or building. However, there are a few commonly used fonts that are often seen on address numbers:

1. Helvetica: Helvetica is a widely recognized and versatile font that is commonly used for various purposes, including address numbers. Its clean and simple design makes it a popular choice for contemporary or minimalist styles.
2. Times New Roman: Times New Roman is a classic serif font that is frequently used for formal documents and publications. Its traditional and elegant appearance can be suitable for more traditional or formal settings.
3. Arial: Arial is a sans-serif font that is similar to Helvetica but has slightly different characteristics. It is often chosen for its readability and modern look, making it suitable for a range of applications, including address numbers.
4. Futura: Futura is a geometric sans-serif font that has a distinct modern and futuristic appearance. Its clean lines and geometric shapes make it a popular choice for contemporary and architectural designs.
5. DIN: DIN is a sans-serif font that originated in Germany and has gained popularity for its clear and efficient design. It is often used for signage, including address numbers, due to its legibility and industrial aesthetic.

Ultimately, the choice of font for address numbers depends on the specific context and desired style. It’s essential to consider factors such as readability, legibility from a distance, and how well the font complements the overall design of the building or neighborhood.