Evaluate 5!4!

$5! 4!$

Expand $5!$ to $5 \cdot 4 \cdot 3 \cdot 2 \cdot 1$ .

$5 \cdot 4 \cdot 3 \cdot 2 \cdot 14!$

Simplify.

Multiply $5$ by $4$ .

$20 \cdot 3 \cdot 2 \cdot 14!$

Multiply $20$ by $3$ .

$60 \cdot 2 \cdot 14!$

Multiply $60$ by $2$ .

$120 \cdot 14!$

Multiply $120$ by $1$ .

$1204!$

Expand $4!$ to $4 \cdot 3 \cdot 2 \cdot 1$ .

$120 (4 \cdot 3 \cdot 2 \cdot 1)$

Simplify.

Multiply $4$ by $3$ .

$120 (12 \cdot 2 \cdot 1)$

Multiply $12$ by $2$ .

$120 (24 \cdot 1)$

Multiply $24$ by $1$ .

$120 \cdot 24$

Multiply $120$ by $24$ .

$2880$