Fill in a number in the tens and ones of the three-digit number 5□□ so that it can be divisible by both 3 and 5. How many filling methods are there?
在三位数5□□的十位和个位各填上一个数字，使它既能被3整除，又能被5整除，有多少种填法．
<gadget id="calculator">3 + 3</gadget>
<output>6</output>

<result>6</result>