1. Meaning: an object, a figure and a unit of measurement can all be regarded as the unit "1". Divide the unit "1" into several parts on average, and the number representing such a part or parts is called a fraction. In the fraction, the denominator indicates how many shares the unit "1" is divided into, and the numerator indicates how many shares there are; One of them is called fractional unit.

2. Nature

(1) The horizontal line in the middle of the score is called the fractional line, the number above the fractional line is called the numerator, and the number below the fractional line is called the denominator. Read it as a score.

(2) Fractions are either finite decimals or infinite cyclic decimals, and infinite acyclic decimals like π cannot be replaced by fractions.

(3) When the numerator and denominator are multiplied or divided by the same number (except 0), the fractional value will not change. Therefore, each score has an infinite number of equal parts. Using this property, we can be on and off.

Fraction originally refers to a part of the whole, or more generally, to any equal number of parts. The form of expression is the ratio of integer A to integer B (whether a false score in multiples of b is a score is controversial). Fraction indicates the fraction of one number to another, or the ratio of one event to all events.

Divide the unit "1" into several parts on average, and the number representing such a part or parts is called a fraction. The numerator is above and the denominator is below. When the denominator is 100, it can be written as a percentage, such as 1%.

The simplest fractional decimal is a prime factor based on the denominator. If there are only 2 and 5, they can be converted into finite decimals; Otherwise, they cannot be converted into finite decimals. What can be judged is not the simplest definite value of the score.

Precautions:

1, the denominator must not be 0, because the denominator is equivalent to a divisor. Otherwise, the equation cannot be established, and the molecule can be equal to 0, because the molecule is equivalent to the dividend. It is equivalent to dividing 0 by any number. No matter what the denominator is, the answer is 0.

2. The numerator or denominator in a fraction cannot have irrational numbers (such as the square root of 2) after reduction, otherwise it is not a fraction.

3. Only two prime factors 2 and 5 in the denominator of the simplest fraction can be converted into finite decimals; If the denominator of simplest fraction only contains prime factors other than 2 and 5, it can become a pure cyclic decimal; If the denominator of simplest fraction contains both prime factors of 2 or 5 and prime factors other than 2 and 5, it can be converted into mixed cyclic decimals.