Adding and Subtracting Fractions with Number Lines
Number lines can be used to find equivalent fractions of the same denominator for two fractions with unlike denominators such as \(\dfrac{2}{3}\) and \(\dfrac{1}{4}\).
The picture below illustrates \(\dfrac{3}{8}+\dfrac{1}{3}\). The common denominator for \(8\) and \(3\) is \(24\). The green tick marks divide the whole into \(24\)ths.
The bottom number line shows the addition of the two fractions with the whole divided into \(24\)ths.
\[\dfrac{3}{8}+\dfrac{1}{3}=\dfrac{17}{24}\]
- How many number lines were used? Why?
- How were the number lines partitioned?
- Use multiple number lines to add: \(\dfrac{1}{3}+\dfrac{1}{6}\)
- Show how the same number line strategy will work to subtract: \(\dfrac{3}{8}-\dfrac{1}{3}\)
