Native Japanese Numbers
In Japanese there are two numerical system. One is the numbers you have already learned, Chinese origin numbers, and the other is the native Japanese numbers. The native Japanese numbers are limited to one through ten.
For things which are not clearly categorized or which are shapeless (stones, boxes, stars, idea, problem etc.), the native Japanese numbers are used. Counting things can be done in two ways.
“Nin” is used for counting people, though one person and two persons are irregular.
Each language has different ways of counting objects. Japanese uses counters. They are similar to English expressions such as “a cup of ~,” “a sheet of ~” and so on. There are a variety of counters, often based on the shape of the object. The counters are attached directly to a number (e.g. ni-hai, san-mai). When combining a number with a counter, the pronunciation of the number or the counter might change.
Another thing I want to mention is when grouping objects, Japanese divide them into groups of five and ten unlike six and twelve in the West. For example, sets of Japanese dishes or bowls are sold in units of five. Traditionally, there was no word for dozen, though it has been used because of Western influence.
When using a counter, pay attention to the word order. It is different from English
order. A typical order is “noun + particle + quantity — verbs.”