1+1 equals 2.

According to Peano's axiom: If b and c are both successors of the natural number a, then b = c;, we can get: 1+1=2. In mathematics, there is another very famous "(1+1)", which is the famous Goldbach's conjecture. Although it sounds mysterious, the questions are not difficult to understand, and anyone with a third-grade elementary school mathematics level can understand its meaning.

Introduction to addition

1. Addition (usually represented by the plus sign "+") is one of the four basic operations of arithmetic, the others are 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".

2. In addition to calculating fruits, other physical objects can also be calculated. Using systematic generalization, addition can also be defined on more abstract quantities, such as integers, rational numbers, real and complex numbers and other abstract objects such as vectors and matrices.

3. Addition has several important properties. It's commutative, which means the order doesn't matter, and it's associative, which means when adding more than two numbers, the order in which the additions are performed doesn't matter. Repeatedly adding 1 is the same as counting; adding 0 does not change the result. Addition also follows related operations such as subtraction and multiplication.

4. Addition is one of the simplest number tasks. The most basic addition: 1 + 1, can be calculated by babies as young as five months old, and even by other animal species. In primary education, students are taught to perform summation calculations of numbers in the decimal system, starting with one-digit numbers and working their way up to more difficult number calculations.