0.04 means 4 hundredths. Write as 4/100, then simplify by dividing numerator and denominator by their HCF.

As a fraction	=	0.04 = \(\frac{4}{100}\)
HCF of 4 and 100	=	4
Simplify	=	\(\frac{4 \div 4}{100 \div 4} = \frac{1}{25}\)