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Countdown knowledge points of sixth grade in primary school
The knowledge points of the sixth grade countdown are as follows:

The reciprocal of the sixth grade in primary school is an important concept in mathematics, which involves the reciprocal of fractions, decimals and integers.

Basic concepts of 1 and reciprocal;

The reciprocal refers to the ratio between a number and 1. It can also be understood that the reciprocal of this number is the result of 1 divided by this number. For example, the reciprocal of the number x is 1/x, if x is not equal to zero, its reciprocal is 1/x, if x is equal to zero, there is no reciprocal.

2, the reciprocal of a positive number:

The reciprocal of a positive number is another positive number. For example, the reciprocal of 5 is 1/5, and the reciprocal of 1/3 is 3. The reciprocal of a positive number is a small fraction, which is numerically smaller than the original number.

3, the reciprocal of zero:

Zero has no reciprocal. Because it is meaningless to divide any number by zero. Therefore, the reciprocal of zero is undefined.

4, the reciprocal of the negative number:

The reciprocal of a negative number is another negative number. For example, the reciprocal of -2 is-1/2, the reciprocal of 1 is-1, and the reciprocal of 1/3 is -3.

5, the reciprocal of the score:

The reciprocal of all non-zero fractions x is equal to the new fraction represented by exchanging the numerator and denominator of this fraction. For example, the reciprocal of 1/4 is 4/ 1, and the reciprocal of 3/5 is 5/3.

6, the reciprocal of the decimal:

If you want to find the reciprocal of a decimal, you can first convert the decimal into a number and then find the reciprocal. For example, 0.2 is converted into a fraction of 1/5, so the reciprocal of 0.2 is 5.

7, the reciprocal of the integer:

The reciprocal of an integer can be divided into two situations: first, the reciprocal of a positive integer is still the reciprocal of a positive integer; Second, the reciprocal of a negative integer is still the reciprocal of a negative number.

8, reciprocal algorithm:

There are some basic algorithms for reciprocal. For example, the reciprocal multiplication of two numbers is equal to the reciprocal of the sum of the reciprocal of these two numbers, that is, (1/x) * (1/y) =1/(xy).

9. The application of reciprocal in practice:

Reciprocal has many applications in practice, such as the calculation of speed, the solution of proportion, the calculation of probability and so on. Understanding the concept and algorithm of reciprocal can help us solve practical problems.