Approximation

[yuē fēn]
Mathematical terminology
Collection
zero Useful+1
zero
The process of reducing the common factor of a fraction's numerator and denominator is called canceling. [4 ]
Approximation is Fractional reduction , put a fraction of molecule denominator At the same time, divide by the common divisor, and the value of the fraction remains unchanged. The basis of reduction is Basic Properties of Fraction When reducing minutes, if you can quickly see the numerator and denominator Maximum common factor It is easy to remove them directly by their greatest common divisor.
Chinese name
Approximation
Foreign name
Reduction
Methods
Same as divided by common divisor
Principle
Equipartition principle
Discipline
Mathematical Science

Introduction to relevant knowledge

Announce
edit

fraction

Fractions (from Latin, "broken") represent parts of a whole, or more generally, any equal number of parts. When speaking in everyday English, scores describe parts of a certain size, such as half, five eighths, and three quarters. Numerators and denominators are also used for uncommon fractions, including compound fractions, complex fractions, and mixed numbers.
A fraction represents the fraction of one number to another, or the ratio of one event to all events. Divide the unit "1" into several equal shares, and the number representing such a share or shares is called fraction. The numerator is above and the denominator is below. [1]

Minimalist fraction

Molecules denominator only Common factor The fraction of 1 is called the simplest fraction or the numerator and denominator are Coprime number The fraction of is called the simplest fraction, also called the reduced fraction. For example: 2/3, 8/9, 3/8, etc.
The simplest fraction is also called both Approximation Number, a reduced fraction can be understood as a fraction that has been reduced, that is, a fraction whose numerator and denominator are coprime numbers.

definition

Announce
edit
Convert fractions into Minimalist fraction The process is called reducing points.
For example, a/b is a fraction, a can be written as c * d, b can be written as c * e, and a/b can be written as d/e, because there is a common factor, c, which can be both the numerator and denominator.

step

Announce
edit
1. Factorize the numerator and denominator;
2. Find the molecule denominator Common factor
3. Remove the non 1 common factor.
When dividing, if you can quickly see the greatest common factor of the numerator and denominator, it is easier to remove them directly with their greatest common divisor.

Reduction method

Announce
edit
According to the basic nature of fractions:
"The numerator and denominator of a fraction are divided by the same number (except 0) at the same time, and the size of the fraction remains unchanged - the basic properties of the fraction".
Method 1 : can be removed by common factor (except 1) of numerator and denominator
Example:
be
Is the simplest fraction
In this way, a fraction that is equal to it but has a small numerator and denominator is called a reduction (usually reduced to the simplest fraction)
Method 2 : Directly remove with the greatest common factor (except 1) of the numerator and denominator of the fraction
Example:
be
Is the simplest fraction
Summary: Generally, the common factor (except 1) of the numerator and denominator is used to remove the numerator and denominator of a fraction until the simplest fraction.

Example

Announce
edit
Writing method:
(The number except for is crossed out, such as 6, 12, 30 and 15 in this example)
You must pay attention to finding the numerator and denominator Common factor , cannot just take the denominator Simplification Or molecular simplification, the common factor of even numbers must have 2, so you can divide by 2 first, then divide slowly, and then multiply all your divisors to get their Maximum common factor

Historical statement of reduction

Announce
edit
Ancient China《 Chapter Nine Arithmetic 》It says in:
"Approximation, half is half, and the other half is not denominator The number of molecules should be reduced from less to more. It shall be approximately equal. " [2]

Skillfully use difference to reduce points

Announce
edit
When the numerator and denominator of a fraction are relatively large, it is often hard to see how much to use to reduce the fraction. Sometimes, the difference between the numerator and denominator can be used to reduce the fraction.
For example, put
Reduction is the simplest fraction.
answer:
about
The difference between 36 and 30 is 6. Use 6 to remove the numerator and denominator, that is
, so 6 is the greatest common factor of the numerator and denominator,
about
The difference between 95 and 57 is 38. According to the oral calculation, 38 is not a factor of the numerator and denominator. Then decompose 38 into a factor, that is, 38=19 x 2. Using 19 to divide, 19 is a factor of the numerator and denominator
about
For example, its numerator and denominator are very different, and the difference is not a factor of the numerator and denominator. It is also troublesome to decompose the difference into factors. At this time, we can use the difference obtained by subtracting a number of decimals from a large number to reduce points, that is, 493-145 x 3=58. When 58 is divided into factors, 58=29 x 2, and 29 is the factor of numerator and denominator, we can get the reduced points
[3]