What mathematical operation increases the value of a quantity by the value of another quantity?

Addition is the mathematical operation that increases the value of a quantity by the value of another quantity. When you add two numbers, you are combining their values together. For example, if you have a quantity of 5 and you add 3, the result is 8, which is greater than both original quantities. This operation is fundamental in mathematics, particularly in early childhood education, as it lays the groundwork for understanding more complex arithmetic operations and quantitative reasoning.

In contrast, subtraction decreases a quantity, while multiplication and division serve different purposes. Multiplication can be viewed as repeated addition, and it may also increase a quantity but in a specific context (e.g., scaling). Division, on the other hand, is the operation that breaks down a quantity into smaller parts, effectively reducing its value. Therefore, addition distinctly stands out as the correct choice for increasing a quantity.