A, B, and C go to the library to read books. A goes once every 3 days, B once every 4 days, and C once every 5 days. They meet in the library on April 13. How many days will it take for them to meet again?
甲、乙、丙三人去图书馆看书，甲3天去一次，乙4天去一次，丙5天去一次，4月13日在图书馆相遇，再过多少天他们才能相遇？
<gadget id="calculator">3 * 4 * 5</gadget>
<output>60</output>

<result>60</result>