What should I write in junior high school mathematics handwritten newspaper?

According to the decimal bit value principle, the decimal part is written in the form without denominator, which is called decimal. The point in the decimal is called the decimal point, which is the dividing line between the integer part and the decimal part of a decimal. The part to the left of the decimal point is an integer part, and the part to the right of the decimal point is a decimal part. Decimals with zero integer parts are called pure decimals, and decimals with non-zero integer parts are called decimals. For example, 0.3 is pure decimal, 3. 1.

Edit the basic properties of this paragraph

Add 0 or delete 0 at the end of the decimal, and the decimal size remains the same. But the counting unit has changed.

Edit the meaning of this paragraph.

We can start with the meaning of fraction, and we can explain it from the activities of block and synthesis. When a whole (reference quantity) is divided into equal parts, the quantity that gathers one part is called "component", and this "component" is expressed or recorded by "fraction". For example, 2/5 refers to the "component" in which an integer is divided into five equal parts and then aggregated into two halves. When the whole is divided into 10, 100, 1000, etc. Use another method to record the weight at this time-decimal. For example,110 is 0. 1, 2/ 100 is 0.02, 5/ 1000 is 0.005 and so on. The "."is called the decimal point, which is used to separate the integer part from the decimal part that cannot form an integer. Integers that are not 0 are called decimals, and those that are 0 are called pure decimals. So the meaning of decimals is part of the meaning of fractions.

Edit this paragraph as.

There are two kinds: one is to read by fractions, and the integer part with decimals is read by integers; The fractional part is read by the fraction. For example, 0.38 is pronounced as 38%, and 14.56 is pronounced as 14 and 56%. In another reading method, the integer part is still read as an integer, and the decimal point is read as a "dot". The decimal part reads the numbers on each digit in sequence. If several zeros are repeated, reading only one zero is not allowed. For example, 0.45 is read as 0.45. 56.032 is read as 56.032; 1.0005 is pronounced one point zero five.

Edit this paragraph comparison

The comparison method of decimal size is basically the same as that of integer, that is, the numbers on the same digit are compared in turn from the high position. Therefore, to compare the sizes of two decimals, first look at their integer parts, and the larger the integer part, the larger the number; If the integer parts are the same, the one with the largest number in the tenth place is larger; If the deciles are the same, the percentile is larger; Because decimals are decimal fractions, they have the following properties: ① Add or remove zero at the end of decimals, and the size of decimals remains unchanged. For example; 2.4 = 2.400, 0.060 = 0.06.② When the decimal point moves one, two or three places to the right, the decimal size will change, and the decimal value will be enlarged by 10 times, 100 times and 1000 times respectively ... for example, 7.4. Enlarging 100 times is 740 ... If the decimal point is moved to the left by one, two and three places respectively, the decimal value will be reduced to one tenth, one hundredth and one thousandth respectively ... For example, reducing 7.4 to 1 is 0.74, and reducing it to one hundredth is 0.074. ...

Edit this paragraph to keep.

Keep decimals: round off some of the most important figures as needed. Infinitely circulating decimals can only be expressed by decimals but not by fractions, while all finite decimals and infinitely circulating decimals can be expressed by fractions. Decimals can be divided into finite decimals and infinite decimals, such as 1/5. Infinite decimal includes infinite acyclic decimal (such as 0.0 100 1 ...) and infinite cyclic decimal (such as 1/3) (rational number): a number that can be accurately expressed as the ratio of two integers, such as 3, -98. 10. 7/22 is a rational number. Integers and fractions are rational numbers. Rational numbers can also be divided into positive rational numbers, 0 and negative rational numbers. In the decimal representation system of numbers, rational numbers can be expressed as finite fractions or infinite cyclic fractions. This definition also applies to other decimals (such as binary). So China Encyclopedia (Mathematics) multiplies decimals with integers: the decimal multiplication is converted into integer multiplication calculation. First, the decimal is expanded into an integer, and the product will be reduced by multiplying the expansion factor by the integer. The decimal places of the product are related to the decimal places of the multiplicand. If the multiplicand has several decimal places, so does the product. Because to convert decimal multiplication into integer multiplication, the product will be amplified as many times as the multiplicand. So how many times must the product be reduced? Calculate decimal multiplication with integers. First, calculate the product according to the calculation method of integer multiplication, and then see how many decimal places the multiplicand has. Count a few from the right of the product and point to the decimal point.

Edit some decimal type definitions in this paragraph.

Pure decimal system

If the integer part is zero, such as 0. 1, the absolute value must be less than 1. Such as: 0.12; 0.945; 0.403 and so on

With decimals

If the integer part is a decimal above 1 or 1, such as 1. 1, the absolute value must be greater than or equal to 1. Such as:1.2345; 9.45; A decimal, such as 1.43, starts from somewhere in the decimal part, and one or several numbers are repeated in turn. This decimal is called a cyclic decimal.

repetend

The decimal part of cyclic decimal is called the cyclic part of cyclic decimal. For example: 0.33 ... the cycle part is "3" 2.14242 ... the cycle part is "42" pure cycle decimal: the cycle part starts from the first place in the decimal part. (Example: 0.666 ...) Mixed cycle decimal: the cycle part does not start with the first decimal part. (Example: 0.5666 ...)

Edit this paragraph for annotation.

When writing cyclic decimals, for simplicity, only the first cyclic segment is written in the cyclic part of decimals. If there is only one number in the loop, add a dot to this number; If there are multiple numbers in the loop part, please add a dot to the first and last numbers in this loop part.

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