Quantity refers to the amount or number of items in a group. It can be measured in various ways, such as counting discrete objects like apples or measuring continuous items like water in liters. Understanding quantity helps in comparing sizes, making decisions, and performing calculations in everyday life. In mathematics, quantity is often represented by numbers and can be classified as either discrete or continuous. Discrete quantities involve whole numbers, such as the number of students in a classroom, while continuous quantities can take any value within a range, like the temperature in a room.