There is a basket of eggs in the basket, every 5 are in a bag, there is 1 left, every 4 are in a bag, or 1 is left, what is the minimum number of eggs in this basket?
篮子里有一筐鸡蛋，每5个装一袋，还剩1个，每4个装一袋，还是剩1个，这筐鸡蛋最少有多少个？
<gadget id="calculator">4 * 5</gadget>
<output>20</output>

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

<result>21</result>