How many different four-digit numbers can be formed by using 1, 1, 2, 3, and 4 in four consecutive grids.
用1，1，2，3，4排在连续的四个格子里，能形成多少个不同的四位数．
<gadget id="calculator">4 * 3 * 2 * 1</gadget>
<output>24</output>

<gadget id="calculator">3 * 4 * 3</gadget>
<output>36</output>

<gadget id="calculator">24 + 36</gadget>
<output>60</output>

<result>60</result>