Find the union and the intersection of the sets $A=\{0,2,4,6,8,\cdots\}$ and $B=\{1,3,5,7,9,\cdots\}$.

Problem: 

Find the union and the intersection of the sets $A=\{0,2,4,6,8,\cdots\}$ and $B=\{1,3,5,7,9,\cdots\}$.

Answer: 

$A\cup B$ is the set of natural numbers and $A\cap B$ is the empty set.