1. The problem is to express the decimal 0.625 as a fraction in its simplest form. 2. To convert a decimal to a fraction, write the decimal as a ratio of two integers, where the denominator is a power of 10 based on the number of decimal places. 3. Since 0.625 has three decimal places, write it as $\frac{625}{1000}$. 4. Simplify the fraction by finding the greatest common divisor (GCD) of 625 and 1000. 5. The GCD of 625 and 1000 is 125. 6. Divide numerator and denominator by 125: $\frac{625 \div 125}{1000 \div 125} = \frac{5}{8}$. 7. Therefore, 0.625 expressed as a fraction in simplest form is $\frac{5}{8}$.