1. The problem is to multiply 40 by 8.10. 2. The multiplication formula is straightforward: $$a \times b$$ where $a=40$ and $b=8.10$. 3. Multiply the numbers: $$40 \times 8.10 = 324$$. 4. This means 40 groups of 8.10 equals 324. 5. So, the final answer is 324.