1. Let's understand why the constant $k$ is used in mathematics and science. 2. The constant $k$ often represents a proportionality constant in formulas, which helps relate two quantities that change together. 3. For example, in Hooke's Law, the force $F$ exerted by a spring is proportional to the displacement $x$, written as $F = kx$, where $k$ is the spring constant. 4. Using $k$ allows us to express relationships clearly and calculate unknown values when one quantity changes. 5. It also helps standardize formulas so they can be applied to different situations by adjusting $k$ accordingly. 6. In summary, $k$ is a useful symbol to represent constants that define how variables relate to each other in equations.