2. Inputting a positive integer $n$ into a machine will produce a positive integer $\frac{n(n+1)}{2}$. If 5 is input into the machine, and then the number produced is input into the machine again, the final number produced by the machine is $\qquad$ .
2. 120 .

The first result is $\frac{5(5+1)}{2}=15$;
The second result is $\frac{15(15+1)}{2}=120$.