If $A = \{1, 2, 3, 4\}$,$B = \{3, 4, 5, 6\}$,$C = \{5, 6, 7, 8\}$,and $D = \{7, 8, 9, 10\}$,find $A \cup B \cup C$.

Find the union of each of the following pairs of sets:
$A = \{ x : x \text{ is a natural number and } 1 < x \le 6 \}$
$B = \{ x : x \text{ is a natural number and } 6 < x < 10 \}$

Given the sets $A = \{1, 2, 3\}$,$B = \{3, 4\}$,and $C = \{4, 5, 6\}$,find $A \cup (B \cap C)$.

If $A$ and $B$ are two non-empty sets,then $(A - B) \cup (B - A)$ is equal to:

Two dice are thrown. The events $A, B$ and $C$ are as follows:
$A:$ getting an even number on the first die.
$B:$ getting an odd number on the first die.
$C:$ getting the sum of the numbers on the dice $\leq 5$.
Describe the event $A \cap B^{\prime} \cap C^{\prime}$.

Show that for any sets $A$ and $B$,$A = (A \cap B) \cup (A - B)$ and $A \cup (B - A) = (A \cup B).$