1/3 0.333333333333. 2/3 0.6666666666666666 unless i've got your question wrong. haha
What definition of "decimal fraction" are you using? In mathematics the precise words of definitions are crucial- and sometimes different people or different books use slightly different definitions. For example, Wikipedia says "A decimal fraction is a fraction whose denominator is a power of ten" so that "1/2" would NOT be a "decimal fraction" but "5/10" would be. That is, a "decimal fraction", by that definition, is a property of the particular way a number is written, not the number itself. "3" is not a "decimal fraction" because it is not a fraction. But "3/1" or "30/10", both of which are equal to 3, are "decimal fractions".