3. (8 points) As shown in the figure, in a multiplication vertical calculation, 2, 0, 1, 6 have already been filled in. What is the product? 

保留源文本的换行和格式，直接输出翻译结果。 

Note: The last line "保留源文本的换行和格式，直接输出翻译结果。" is in Chinese and is not part of the translation. It is an instruction to maintain the original text's line breaks and format.
【Solution】Solution: First, judge according to the number 0, the tens place of the first number is 5, only $2 \times 5=10$ meets the condition. So the digit before 0 is 1.

Then, judge according to the number 6, which is $1+5=6$, the digit above 6 is 5. The first two-digit number 51 appears.
So in the multiplication, only the digit 1 before 2 meets the condition, and the digit after 0 is 2.
That is, $51 \times 12=612$.
Therefore, the answer is: 612