1, the fractional multiplication of integers has the same meaning as integer multiplication, and it is a simple operation to find the sum of several identical addends. Multiplying a number by a fraction can be regarded as finding a fraction of this number. ?

2. Fraction multiplied by integer: combination of numbers and shapes, and conversion.

3. The basic nature of the ratio: the first and second items of the ratio are multiplied or divided by a non-zero number, and the ratio remains unchanged. ?

4. If a number is greater than zero (> 0), it is called a positive number. Positive numbers can be preceded by a plus sign. There are countless kinds of positive numbers, including positive integers, positive fractions and positive irrational numbers.

5. The two circular surfaces of the cylinder are called the bottom surface (divided into the upper bottom and the lower bottom); A cylinder has a curved surface called a side surface; The distance between two bottom surfaces is called height (there are countless heights).