This is mathematical addition: 1+2=3.

The addition operation here is within the parentheses and has the right to be calculated first, such as (1+2)×3. Although there is multiplication, the priority of the parentheses is higher than the multiplication. The inside of the parentheses is calculated first and the outside of the parentheses is calculated. .

Addition (usually represented by the plus sign "+") is one of the four basic operations of arithmetic, the others being subtraction, multiplication and division. For example, in the picture below, there are combinations of three apples and two apples, for a total of five apples. This observation is equivalent to the mathematical expression "3 + 2 = 5", i.e. "3 plus 2 equals 5".

Extended information:

Addition is written with a plus sign "+" between terms; the result is represented by an equal sign. For example,

There are also cases where a number followed by a fraction represents a mixed number, even if no symbol is present.

For example,

This symbol may be controversial because in most other contexts, two numbers put together represent multiplication.

The sum of a series of related numbers can be represented by the σ symbol, indicating iteration.

For example,