Numerals with ь at the end

Question

Which numerals have a ь at the end and which have in the middle?

Answer 1

Let me jump in with some extracurricular findings.

In speech, some people would palatalize the sound /т/ and you'll have a /т'/ gravitating towards /ц/ at the end of these numerals:

50 - пятьдесят 60 - шестьдесят 70 - семьдесят 80 - восемьдесят 500 - пятьсот 600 - шестьсот и т.д.

This phenomenon doesn't affect the spelling, but you'd hear the palatalization, which may be confusing. Keeping this in mind may be of use when working on a transcript. Say, /пятьдесять/ pops up in someone's speech, and you're in two minds about how to spell it.

Also, according to this source, they used to spell these numerals with "ь" at the end in the 17th century.

Answer 2

Many have an "ь" in the end:

5 - пять  
6 - шесть 
7 - семь 
20 - двадцать
30 - тридцать
и т.д.

And many have a "ь" in the middle:

50 - пятьдесят
60 - шестьдесят
70 - семьдесят
80 - восемьдесят
500 - пятьсот
600 - шестьсот
и т.д.

Answer 3

Which numerals have a 'ь' at the end?

5 - пять
6 - шесть
7 - семь
8 - восемь
9 - девять
10 - десять
11 - одиннадцать
12 - двенадцать
13 - тринадцать
14 - четырнадцать
15 - пятнадцать
16 - шестнадцать
17 - семнадцать
18 - восемнадцать
19 - девятнадцать
20 - двадцать
30 - тридцать

Which numerals have a 'ь' in the middle?

50 - пятьдесят
60 - шестьдесят
70 - семьдесят
80 - восемьдесят
500 - пятьсот
600 - шестьсот
700 - семьсот
800 - восемьсот

About pronunciation:
Numbers 11-30 (which I have written) ends with т' if pronounced slowly and т' with approach to ц' in fluent speech.