math
posted by Linda Delorme .
how many possible 3 digit numbers are there that have a middle zero? how many possible 4 digit numbers are there that have 2 middle zero? explain your answear

In both cases, the zeros are constant. The first number can vary 19 (since 00x or 000x are not numbers), while the last number can vary from 09. Thus there are 9 possibilities for the first number and 10 for the last.
You should be able to take it from here.
I hope this helps. Thanks for asking.