什麼是Counting number???

Counting Numbers are different than real numbers in several key respects. First, they begin at "1", there is no "0" in counting numbers. The most well known historical example of counting numbers are Roman Numerals which begin with I then II and so on. There is no Roman Numeral for "zero" as there is never any need for zero in systems based on Counting Numbers. The first thing counted, whatever it may be is labeled "1". Each additional thing gets a progressively higher number.

Generally speaking Counting Numbers are 1 higher than the Real Number equivalent.

所以0 唔係counting number
u can take the example of " months named" ...like...there is no such month called "0月"
just from 1月~12月~

希望幫到你 : )