4 89/100
489/500
4.89 = 489/100
examples:(a) 4.89= 489/100
4.89 is a rational number because it can be expressed as a fraction in the form of 489/100
You could leave it as 0.489 so that it is a fraction in decimal form rather than in the form of a ratio. That does not stop it being a fraction. Its rational equivalent is 489/1000 which cannot be simplified.