1. The problem is to multiply 18 by 5. 2. The formula for multiplication is $a \times b = c$, where $a$ and $b$ are numbers and $c$ is their product. 3. Here, $a = 18$ and $b = 5$. 4. Multiply the numbers: $$18 \times 5 = 90$$ 5. So, the product of 18 and 5 is 90.