How many different methods are there to take 3 out of 9 digits from 1 to 9 so that their sum is a multiple of 3?
从l～9这9个数码中取出3个，使它们的和是3的倍数，则不同取法有多少种．
<gadget id="calculator">3 * 3 * 3</gadget>
<output>27</output>

<gadget id="calculator">1 + 1 + 1 + 27</gadget>
<output>30</output>

<result>30</result>