Throw 4 identical small cubes at the same time (the numbers 1, 2, 3, 4, 5, and 6 are written on the six sides of the small cubes), how many kinds of sums are there for the 4 numbers on the upward side?
同时掷4个相同的小正方体(小正方体的六个面上分别写有数字1、2、3、4、5、6)，则朝上一面的4个数字的和有多少种．
<gadget id="calculator">6 * 1 * 4</gadget>
<output>24</output>

<gadget id="calculator">1 * 4</gadget>
<output>4</output>

<gadget id="calculator">24 - 4</gadget>
<output>20</output>

<gadget id="calculator">20 + 1</gadget>
<output>21</output>

<result>21</result>