What is the numbers on fire extinguishers?

The numbers on fire extinguishers indicate their classification and effectiveness against specific types of fires. For example, a fire extinguisher marked with a "2A:10B:C" label is effective for Class A (ordinary combustibles), Class B (flammable liquids), and Class C (electrical) fires. The number before the letter indicates the size or capacity of the extinguisher and its effectiveness rating for that class. Always choose the appropriate extinguisher based on the type of fire you may encounter.