There are some digital cards, the numbers written on them are all multiples of 2 or multiples of 3, among which cards with multiples of 2 account for (3/5), cards with multiples of 3 account for (5/6), and cards with multiples of 6 have 13, so how many cards are there in total?
有一些数字卡片，上面写的数都是2的倍数或3的倍数，其中2的倍数的卡片占(3/5)，3的倍数的卡片占(5/6)，6的倍数的卡片有13张，那么这些卡片共有多少张．
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">5 / 6</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">(5/6) - 1</gadget>
<output>-1/6 = around -0.166667</output>

<gadget id="calculator">(3/5) + (-1/6)</gadget>
<output>13/30 = around 0.433333</output>

<gadget id="calculator">13 / (13/30)</gadget>
<output>30</output>

<result>30</result>