1=0+ 1= 1+0, so there are two simple ordered pairs 1 (0, 1, 0);
9 = 0+1=1+8 = ... = 9+0, with10;
4, there are 5;
2 has 3;
According to the principle of multiplication, the total number is 2x 10x5x3=300.
I hope it helps you!