A decimal fraction is a fraction that has what as a denominator?

A decimal fraction is defined specifically as a fraction where the denominator is 10 or a power of 10, such as 100, 1000, and so forth. This characteristic allows decimal fractions to be expressed in a numerical format that uses a decimal point, making it easier to represent values less than one and to perform arithmetic operations.

The connection to powers of 10 is crucial because it directly relates to the positional value of digits in decimal notation. For instance, the fraction 3/10 can be written as 0.3, indicating that the digit 3 is in the tenths place. Similarly, the fraction 45/100 can be expressed as 0.45, with the digit 4 representing four tenths and the digit 5 representing five hundredths. This systematic relationship helps form the basis for the decimal number system, which is widely used in mathematics and engineering.

The other options, while they describe types of numbers or forms related to fractions, do not accurately define the specific characteristic of a decimal fraction. The requirement for the denominator to be a power of 10 is what distinguishes decimal fractions from simple fractions with other types of denominators.