When 0.4 is written as a fraction, which is the fraction before simplification?

• A. 4/10
• B. 2/5
• C. 1/4
• D. 3/10

Answer: (A)

Understanding what a decimal means in fractions: 0.4 is four tenths. Writing that as a fraction gives 4/10, the unreduced form. You can see it matches 0.4 because 4 divided by 10 is 0.4. If you simplify, you divide numerator and denominator by 2 to get 2/5, which is another way to express the same value. The other options don’t represent four tenths: 1/4 is 0.25, and 3/10 is 0.3. Therefore, the fraction before simplification is 4/10.