How do you use counters past 10?


Counter words have different readings for 1 through 10.  
How do I use them for number 11 and beyond?

Do I change the counter's pronunciation based on the last digit of the number?
So if the number is 21, do I use the reading for 1?

What if it's 20? Would the original counter be used? Like "nijuu-nin" for 20
people? I can't seem to find a guide for using counters past 10.




[Here's an article.](http://www.learn-japanese.info/Counters.html) [And
another article.](http://www.tofugu.com/guides/japanese-counters-guide/)

Also, once you know the counter no matter the number you can use them as
usual.

  * I will buy 2 books = hon o ni satsu kaimasu
  * There are 3 people here = koko ni hito ga san nin imasu
  * There are 20 people = hito ga ni juu nin imasu
  * There are 21 people here = koko ni hito ga ni juu ichi nin imasu
  * I drank 4 cups of coffee = watashi wa koohii o yon hai nomimashita




[Here's an article.](http://www.learn-japanese.info/Counters.html) [And
another article.](http://www.tofugu.com/guides/japanese-counters-guide/)

Also, once you know the counter no matter the number you can use them as
usual.

  * I will buy 2 books = hon o ni satsu kaimasu
  * There are 3 people here = koko ni hito ga san nin imasu
  * There are 20 people = hito ga ni juu nin imasu
  * There are 21 people here = koko ni hito ga ni juu ichi nin imasu
  * I drank 4 cups of coffee = watashi wa koohii o yon hai nomimashita

