Solve the Fraction Addition: 1/2 + 1/9 Step by Step

Because fractions represent parts of different wholes! $\frac{1}{2}$ means 1 part out of 2, while $\frac{1}{9}$ means 1 part out of 9. You need to make the "wholes" the same size first.

The easiest way is to multiply the two denominators together: 2 × 9 = 18. For more advanced problems, you can find the least common multiple (LCM) to get a smaller common denominator.

Not always! If one denominator divides evenly into the other, use the larger one. For example: $\frac{1}{3} + \frac{1}{6}$ uses 6 as the common denominator since 6 ÷ 3 = 2.

Check if the numerator and denominator share any common factors. Since 11 is prime and doesn't divide into 18, $\frac{11}{18}$ is already simplified!

That's okay! You might use the least common multiple instead. For this problem, 18 is actually the LCM of 2 and 9, so you'll get the same answer either way.

You could, but fractions are often more precise. $\frac{1}{2} = 0.5$ and $\frac{1}{9} = 0.111...$ gives 0.611..., which is harder to work with than $\frac{11}{18}$.