This is the 12772nd most frequent Korean word.
더하기
"Addition" or "adding."
'더하기' in this sentence means the mathematical operation of addition.
이 문제를 풀 땐, 두 숫자를 더하기만 하면 돼요.
To solve this problem, you just need to add the two numbers.
'더하기' here implies the action of physically incorporating one element (salt) into another (food recipe).
레시피에 소금을 더하기 전에 맛을 먼저 보세요.
Before adding salt to the recipe, taste it first.
'더하기' in this example is used metaphorically to convey the idea of adding to something abstract, such as achievements.