Find the number of solutions to
x_1 + x_2 + x_3 + x_4 + x_5 + x_6 + x_7 + x_8 + x_9 + x_10 <= 2
in nonnegagive integers.
There are 2 stars and 10 bars which makes for \({12 \choose 10} = \color{brown}\boxed{66}\) combinations.
+2668 
