Mom has some candy. If you share 5 yuan and 5 yuan, you will have 1 yuan left in the end. If you divide it into 4 yuan and 4 yuan, you will have 1 yuan left. How many pieces of candy does your mother have at least?
妈妈有些糖，若5块5块的分，最后余1块，若4块4块的分，也余1块，妈妈至少有多少块糖．
<gadget id="calculator">4 * 5</gadget>
<output>20</output>

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

<result>21</result>