Lesson 2: Find Common Denominators

Property

If one denominator, $d_2$, is a multiple of another denominator, $d_1$, then the larger denominator, $d_2$, can be used as a common denominator.

Examples

Property

A common denominator for two fractions, $\frac{a}{b}$ and $\frac{c}{d}$, can be found visually using two identical area models.
By partitioning the first model (representing $\frac{a}{b}$) with $d$ horizontal lines and the second model (representing $\frac{c}{d}$) with $b$ vertical lines, both models are decomposed into $b \times d$ equal parts.

Examples