1. The problem is to calculate the product of three numbers in each expression. 2. The formula for multiplication of three numbers $a$, $b$, and $c$ is: $$a \times b \times c$$ 3. We will calculate the first expression: $13 \times 38 \times 20$. 4. Multiply the first two numbers: $$13 \times 38 = 494$$ 5. Now multiply the result by the third number: $$494 \times 20 = 9880$$ 6. So, the answer to the first expression is $9880$. Since the user asked multiple expressions but per instructions we solve only the first one, the final answer is $9880$.