The numbers "1.5" and "2.75" are examples of decimal numbers, which represent values between whole numbers. A decimal number consists of a whole part and a fractional part, separated by a decimal point. For instance, "1.5" is one and a half, while "2.75" is two and three-quarters. Decimals are commonly used in various fields, such as mathematics, finance, and science, to express precise measurements or quantities. They allow for more accurate calculations compared to whole numbers. Understanding decimals is essential for tasks like budgeting, cooking, and measuring distances in metric or imperial systems.