# Commutative property

The definition of commutative property of addition is, when we substitute any number for a and b, $a+b=b+a$.
For example, $2+3=3+2$, because $2+3$ and $3+2$ are both $5$. It doesn't matter whether the $2$ or the $3$ comes first. 2+3=3+2 is the same as $a+b=b+a$, when $a=2$ and $b=3$.
We can substitute fractions too. $\frac{1}{2}+\frac{1}{3}=\frac{1}{3}+\frac{1}{2}$. Either way, it adds to $\frac{5}{6}$.
And for good mathematicians, we can substitute irrational numbers as well: $\sqrt{4}+\sqrt{8}=\sqrt{8}+\sqrt{4}$.