Number letter counts
Here are a few things:


container.__len__() – You should never call magic methods directly. Just use len(container).
As you don’t know to what amount you need to increment (i.e. your COUNTTO), it would make more sense to have a while loop that keeps iterating until you reach your final length result:

while length &lt; 1000:
     # do stuff with i
     length += # update length
     i += 1

You could also make use of itertools.count:

length = 0
for i in itertools.count(1):
    length += # update length
    if length &gt; 1000:
        break

not i % 100 == 0 – When you already have a operator (==) then don’t use not to invert the whole condition, but just use the inverted operator: i % 100 != 0
Also having additional counting logic outside of your num2eng does not seem to be appropriate. What does that function do exactly? Shouldn’t it rather produce a real number using a complete logic? Ideally, it should be as simple as this:

length = 0
for i in itertools.count(1):
    length += len(num2eng(i))
    if length &gt; 1000:
        break