In Arabic, every word puts to represent its meaning, that singular represents the singular, dual represents dual, and plural represents plural in order to obtain agreement between the two words to complete the meaning on one hand, but on the other hand there are no agreement between them in the same meaning such as singular represent dual, singular represents plural, dual and plural represent singular, dual represents plural. If the singular represents singular, dual represents dual, and the plural represents plural that means quantity agreement, but if differs that means quantity differences.