tashiざんzan
1.

The mathematical process of combining two or more numbers to find their total, often referred to as finding the sum.

2.

A fundamental operation in arithmetic that involves adding quantities together to yield a single, cumulative amount.

3.

The technique of calculating the sum of multiple numerical values, which is essential for various mathematical computations and applications.

Example:

うちの息子はまだちゃんと足し算ができない。