The sum of the reciprocals of four consecutive natural numbers is equal to (19/20), find the sum of the pairwise products of these four natural numbers.
四个连续自然数的倒数之和等于(19/20)，求这四个自然数的两两乘积之和．
<gadget id="calculator">3 * 4</gadget>
<output>12</output>

<gadget id="calculator">3 * 5</gadget>
<output>15</output>

<gadget id="calculator">3 * 6</gadget>
<output>18</output>

<gadget id="calculator">4 * 5</gadget>
<output>20</output>

<gadget id="calculator">4 * 6</gadget>
<output>24</output>

<gadget id="calculator">5 * 6</gadget>
<output>30</output>

<gadget id="calculator">12 + 15 + 18 + 20 + 24 + 30</gadget>
<output>119</output>

<result>119</result>