1. The problem is to multiply 321.5 by 1.234. 2. The formula for multiplication is straightforward: $$a \times b$$ where $a=321.5$ and $b=1.234$. 3. Multiply the numbers: $$321.5 \times 1.234 = 396.491$$ 4. Explanation: Multiplying a decimal by another decimal involves multiplying as if they were whole numbers and then placing the decimal point in the product according to the total number of decimal places in the factors. 5. Here, 321.5 has 1 decimal place and 1.234 has 3 decimal places, so the product has $1+3=4$ decimal places. 6. The final answer is $$396.4910$$ (or simply $$396.491$$).