A subscript in a formula is a number or symbol written below and to the right of a variable or other mathematical object. Subscripts are used to distinguish between different instances of the same variable or object, or to indicate other specific properties or characteristics.

Here are some examples of how subscripts are used in formulas:

* In the formula \(y = mx + b\), the subscript m indicates the slope of the line, and the subscript b indicates the y-intercept.

* In the formula \(P_n = (1 + r)^n\), the subscript n indicates the number of compounding periods.

* In the formula \(E = mc^2\), the subscript m indicates the mass of the object, and the subscript c indicates the speed of light.

In some cases, subscripts can also be used to indicate the position of an element within a sequence or array. For example, in the formula \(a_i = i^2\), the subscript i indicates the index of the element in the sequence.

Overall, subscripts are an important tool for distinguishing between different instances of variables or objects in mathematical formulas.