From the nine numbers 1 to 9, two numbers are taken each time, and the sum of these two numbers must be greater than 10. How many ways can there be?
从1～9这九个数中，每次取2个数，这两个数的和必须大于10，能有多少种取法．
<gadget id="calculator">7 + 5 + 3 + 1</gadget>
<output>16</output>

<result>16</result>