example

Once upon a time, an old man said to his three sons before he died, "I can't do it." There are only seventeen trees in our house. After I die, the boss will be divided into half, the second child into one third and the boss into one ninth. Besides, no tree can be cut down. "With these words, the old man died.

The three brothers were very sad when they saw their dead father. So they talked about burying their father. They also discussed how to divide the tree according to father's instructions and the old man's will. They can't be separated. The three brothers are at a loss, and no one can do anything.

However, just when they were at their wits' end, a clever child passed by and solved the problem easily. Let's look at his solution.

The children and three brothers said, "If we want to use existing trees, we can't separate them according to your father's instructions, so we need to use outsiders' trees." Hearing this, the three brothers were still puzzled, so the children continued to answer questions for them.

Solution:

Add points from the neighbor's tree, 17+ 1= 18 (tree). Half of the eldest: 18 is the third of the second: 18.

One is 6 (tree): one ninth of 18 is 2 (tree) 9+6+2, which is exactly 17. Finally, return the neighbor's tree to the neighbor.

formula

Fraction: divide the unit "1" into several parts on average, and the number representing such a part or fraction is called a fraction.

1. Law of addition, subtraction, multiplication and division of fractions:

Add and subtract fractions with the same denominator, only add and subtract numerators, and the denominator remains the same.

Fractions of different denominators are added and subtracted, first divided, then added and subtracted.

Multiplication of fractions: use the product of molecules as numerator and the product of denominator as denominator.

Division of fractions: dividing by a number is equal to multiplying the reciprocal of this number.

2. Score comparison: Compared with the denominator, the numerator is large and the numerator is small. Compared with the denominator, the scores of different denominators are divided first and then compared; If the numerator is the same, the denominator is big and small.

3. Fraction multiplied by integer, numerator is the product of fractional and integer multiplication, and denominator remains unchanged.

4. Fractions are multiplied by fractions, the product of numerator multiplication is numerator, and the product of denominator multiplication is denominator.

5. Fraction divided by integer (except 0) is equal to fraction multiplied by the reciprocal of the integer.

6. True fraction: The fraction with numerator less than denominator is called true fraction.

7. False fraction: The fraction with numerator greater than denominator or numerator equal to denominator is called false fraction. False score is greater than or equal to 1.

8. With scores: Write false scores as integers, and true scores are called with scores.

9. The basic nature of the fraction: the numerator and denominator of the fraction are multiplied or divided by the same number at the same time (except 0), and the size of the fraction remains unchanged.

10. A number divided by a fraction is equal to the number multiplied by the reciprocal of the fraction.

1 1.A divided by b (except 0) is equal to the reciprocal of a multiplied by b.