From the ten natural numbers from 1 to 10, randomly pick 2 numbers so that the sum is greater than 10, how many ways are there to choose.
从1至10这十个自然数中，任意取出2个数，使其和大于10，问有多少种取法．
<gadget id="calculator">9 + 7 + 5 + 3 + 1</gadget>
<output>25</output>

<result>25</result>