In mathematics, combination refers to the result of adding two or more numbers. The concept of combination is often used in mathematical reasoning and calculation. It is usually represented by a+sign, for example, 2+3 = 5, which means that the result of adding two numbers, 2 and 3, is 5. In elementary mathematics teaching, combination is one of the earliest basic algorithms, which can help students develop their computing ability and mathematical thinking ability. In addition, combination is also the basis of other algorithms, because operations such as multiplication and division can be realized by using combination many times.

Combination in algebra refers to the result of the addition of two or more polynomials. For example, (3x+4y)+(2x-5y) = 5x-y, in algebra, combination is a very important operation, through which complex algebraic operations such as addition, subtraction, multiplication and division of polynomials can be easily completed. It can be seen that the combination in algebra has something in common with the combination in mathematics, but the combination in mathematics is a logarithmic operation, while the combination in algebra is an operation on polynomials or numbers with higher dimensions, so it can be regarded as a more advanced operation.

Combination can also be used in probability statistics, which usually refers to the result of adding the probabilities of two or more events. For example, when the probability of the heads and tails of a coin is 1/2, the probability of flipping the heads or tails of a coin once is 1/2. Add them up and the probability of flipping a coin is 1. In probability statistics, integral is often used to calculate the probability of complex events, which can help people optimize decision-making and forecast results. It can be seen that combination in probability statistics is very different from combination in mathematics and algebra, but they can get higher-level results by adding multiple basic elements, so it can be said that combination is an important concept in mathematics and widely used in various fields.