1, decimal overview
Decimal refers to a number between integers, which can represent fractions or real numbers. Decimals are widely used in daily life, such as discounts on shopping items, sugar content in drinks and so on.
2. Definition of decimals
Decimal is a finite or infinite decimal between two natural numbers. Among them, the finite decimal refers to the decimal with limited digits after the decimal point, and the infinite decimal refers to the fact that the digits after the decimal point are always more than the limited digits. For example, 0.25 is a finite decimal, and 0.33333 ... is an infinite decimal.
3. Fractional form of decimals
Any decimal can be written in fractional form. The method is to multiply the decimal value by the corresponding fraction according to the number of digits, and then through simplification, you can get a fraction equal to the decimal. For example, 0.5 can be simplified as 1/2, and 0. 16 can be simplified as 4/25.
4, the role of the decimal point
Decimal point is an important symbol in decimal system, which is used to identify the dividing line between integer part and decimal part. Its position determines the size and precision of the decimal. For example, 0. 1 and 0.0 1 are only one decimal place apart, but their sizes are ten times different.
5, four decimal operation
The addition, subtraction, multiplication and division of decimals are similar to the four operations of integers. Among them, addition and subtraction must be aligned with the decimal point before calculation; Multiplication should pay attention to the multiplication rule of decimal places, that is, the result of adding two decimal places is the decimal place of the product; Division requires fractional division. Multiply the divisor and dividend by a multiple of 10 to make them integers, and then calculate.
6. Expand the knowledge of decimals
In the process of learning decimals, many other concepts and knowledge will be involved, such as circulating decimals, rational numbers, irrational numbers, scientific counting methods and so on. A deep understanding of this knowledge can help us better master the application and calculation methods of decimals.
In a word, decimal is one of the important concepts in mathematics and has a wide range of application values. Mastering the definition, four operations and application methods of decimals is not only a compulsory content for students to learn mathematics, but also one of the practical skills in daily life.