When adding fractions, what must be the same?

• A. The numerators
• B. The denominators
• C. The whole numbers
• D. The mixed numbers

Answer: (B)

When adding fractions, it is essential for the denominators to be the same. This is because the denominator indicates how many equal parts the whole is divided into, so having a common denominator allows us to combine the fractions meaningfully.

For example, if you're adding (\frac{1}{4}) and (\frac{1}{2}), you first need to convert (\frac{1}{2}) to a fraction with a denominator of 4, which would be (\frac{2}{4}). Now both fractions have the same denominator, enabling you to add them together: (\frac{1}{4} + \frac{2}{4} = \frac{3}{4}).

Maintaining the same denominator ensures that you are working with fractions that represent equivalent proportions of the same whole, allowing for correct addition.