A rational number is any number that can be turned into a fraction, as 6.43 can be expressed as 643/100 or 1286/200, etc..., it is a rational number.
Rationals include: Whole numbers ( positive numbers , excluding fractions) , integers ( postivie and negative numbers , excluding fractions), fractions, and infinite decimals that repeat ( example 0,3333... can be expressed as 1/3 so it is a rational)