1. The problem is to multiply 25 by 25. 2. The formula for multiplication is $a \times b = c$, where $a$ and $b$ are the numbers to multiply, and $c$ is the product. 3. Here, $a = 25$ and $b = 25$. 4. Multiply the numbers: $$25 \times 25 = 625$$ 5. So, the product of 25 and 25 is 625.