Final answer:
The phrase "many more" typically refers to the operation of addition.
Step-by-step explanation:
The phrase "many more" usually refers to increasing a quantity or adding something additional. When we translate this idea to mathematical operations, it aligns with addition. Therefore, the operation that the words "many more" typically refer to is Option 4: Addition. In a mathematical context, especially when dealing with problems related to money or measurements such as grams and kilograms, "many more" implies increasing the initial amount, which is achieved through the process of adding values together.