I have to incrementally concatenate a given number on each iteration so that it returns a sum and the concatenated string. This is my try:

```
def digit_sum_from_letters(x):
    a = int("%s" % x)
    b = int("%s%s" % (x,x))
    c = int("%s%s%s" % (x,x,x))
    d = int("%s%s%s%s" % (x,x,x,x))
    return a+b+c+d
print digit_sum_from_letters(9) 

```

returning `11106`

But I need to generate the sum for whatever given integer so I need a loop but I'm stuck.

Thanks!