The Japanese language is complex in many ways. One of the most confusing parts to master is using counters. In Japanese, when counting anything, you must use a counter after the number in order to be counting correctly. The counter you use will depend on what it is that you are counting.
Counting People and Animals
For example, people would be counted by adding the suffix –nin, after the number with the exception of one or two people. One person would be counted as hitori, and two as futari. After that, the count would be san-nin, yo-nin, go-nin (three people, four people, five people), etcetera.
Very large animals such as elephants or things such as houses would be counted using the suffix –tou. One rhinoceros would be counted as ittou, and two as nittou, three as santou and so on.
Small to medium-sized animals are counted with the suffix –hiki (-biki, -piki). A dog would be counted using -hiki. One dog would be ippiki, two would be nihiki, three would be sanbiki (follow standard sound variations here when using suffixes) and so on.
Long, Skinny Objects
Long, skinny objects such as pencils, bottles or chop sticks are counted using the suffix –hon (-bon, -pon depending on the number). One pencil would be counted as ippon, and two as ni-hon, san-bon etcetera. After three, most numbers will revert back to the –hon suffix.
Books and Bound Objects
Books, magazines and similar objects are counted with the suffix –satsu.
Days of the Month
Days of the month are also said in different ways. Although you could say nigatsu no sannichi (February 3rd), it is more correct to refer to the numbered days of the month in the following way:
Neutral Number Suffixes and Other Examples of Counters
Other counters exist as well, such as -kai for counting stairs or floors in a building.
Ichi-kai, ni-kai, san-kai
-Sai would be the counter used to count your age, with the exception of the irregular 20 years of age, called hatachi. This could be because turning 20 is a special birthday, regarding as the coming of age for young Japanese becoming adults.
Issai, ni-sai, san-san, …..hatachi (20)
A more neutral suffix for counting would be –tsu. If you are not sure which to use, this one will be more widely understood by the Japanese listener. Adding this suffix to numbers is a little tricky because the first several numbers will take irregular form.
Finally, when using ordinal numbers in Japanese we come to a suffix that is easy to use. Simply add –ban, to the end of a number and you will have its ordinal equivalent.
First = ichiban
Second = niban
Third = sanban
This rule has very little variance and can safely be used up the number line.
- Counting in Japanese Ebook by koichi - http://www.tofugu.com/wp-content/uploads/2008/11/japanesecounters.pdf