Well this one is taking a number and then summing the individual parts till you reach a value of 1, 2, 3, 4, 5, 6, 7, 8, 9, or 0 (only if the original is 0 the answer will be 0). For example:

x = [103]; So ---> 1+0+3 = 4
output  = 4;

another example:

x = [99]; So ---> 9+9 = 18  ---> 1+8 = 9
output  = 9;

another example:

x = [1199]; So ---> 1+1+9+9 = 20  ---> 2+0 = 2
output  = 2;

another example:

x = [11 3]; So ---> 1+1 = 2 and  3 = 3
output  = [2 3];