When wearing beads, there is the following rule from left to right: white red white white red white white white red white white white red... Then when the number of white beads is exactly 4 times that of red beads, at least how many beads are worn.
穿珠子时，从左往右有如下规律：白红白白红白白白红白白白白红…那么当白珠颗数恰好是红珠的4倍时，至少穿了多少颗珠子．
<gadget id="calculator">1 * 5</gadget>
<output>5</output>

<gadget id="calculator">1 + 2 + 3 + 4 + 5 + 5</gadget>
<output>20</output>

<gadget id="calculator">5 + 20</gadget>
<output>25</output>

<result>25</result>