# Decimal fractions

Note the fractions:

The denominators are powers of 10.

Like this:

 They call themselves decimal fractions all fractions that have powers of 10 in the denominator.

The French Viète (1540 - 1603) developed a method for writing decimal fractions. Instead of fractions, Viète would write comma numbers. This modernized method is still used today.

Note in the table the representation of decimal fractions by decimal numbers.

 Decimal Fraction = Decimal numbers = 0,1 = 0,01 = 0,001 = 0,0001
 Decimal Fraction = Decimal numbers = 0,5 = 0,05 = 0,005 = 0,0005
 Decimal Fraction = Decimal numbers = 11,7 = 1,17 = 0,117 = 0,0117

The numbers 0.1, 0.01, 0.001 and 1.17, for example, are decimal numbers. In this representation, we find that the comma separates the whole part from the decimal part.