It is ok for primary schools to divide numbers into integers and fractions, because there is no concept of rational numbers in primary schools, and integers and fractions can completely summarize the scope of primary school mathematics.

The percentage is a fraction, but the denominator is 100, and the numerator is not necessarily an integer. The number of components can be converted, such as 2.75% = 1 1/400. But decimals are different. Elementary school textbooks say that finite decimals and infinitely circulating decimals can be converted into component numbers, such as 3.5 = 7/2, 0.33333...= 1/3, while infinitely circulating decimals are not in the classification of fractions, such as root number 2 = 1.4 142 1.

By the way, I personally think that the general form of the fraction p/q requires that the denominator q is not equal to 1 and that p and q are prime numbers, so 4/2 cannot be regarded as a fraction and needs to be discussed in the simplest form. Otherwise, is the root number 2 of the root number 2 rational or irrational?

By the way, integers and fractions should be positive and negative. .