(i) Find the number of integers between 500 and 5000 that do not contain 0 as a digit.

(ii) How many integers between 500 and 5000 contain the digit 0 exactly once?

(iii) ...at least twice?

---

Assuming that 500 and 5000 are not included,

(i) $\displaystyle (4999-500)-18-4*19-4(100+9*19)=3321$

(ii) $\displaystyle 18*5+4*9*18=738$

(iii) $\displaystyle 4+4(19+9)=116$

I assume these are right(ish), but is there a simpler method?