The existence of number reflects human need to count. Counting has never gone beyond certain boundaries depending upon human needs. People with the exception of a few have always complained about number crunching. On the other hand, business people are said to be highly number literate. Agreement in English grammar has also been a pitfall for mistakes and confusion. In some cultures for example there is no need to count beyond three or four. The existence of words like: show this tendency even in English. In addition, when counting, is taken as singular but anything starting from is plural. Strangely, there is no difference between two and a hundred because both are plural no matter the big difference in number. In some languages there are different kinds of plurals. There is a plural form referring to a small group and another one to a bigger group. Sometimes plural begins from three i.e. after dual which is two as in: the two of you or both of you. This might explain why we easily get confused when we count beyond a million. For example the word in English is not the same in other European languages. It means one thousand million for which the Germans for example have the word . Number together with mathematical operations of addition, subtraction, multiplication and division grew in importance when business developed and became part of everyday life.
This confusion is still persistent for example in: the family is (are) here depending upon your way of seeing the family. If you take the family as a group consisting of members i.e. you know them (personally) use it with a plural verb: the family have arrived. My trousers are old (although one pair); is more than ; coffee is more than coffee. The word number is in itself confusing. is used with a plural verb or countable noun such as: a (large) number of people have attended the party whereas is used with a singular verb: the number of deserters is growing. But if you make the word plural it takes then a plural verb: the numbers of emigrants are rising. The police are here (in other languages the police is here). Words like cannot be counted in English whereas in other language they are counted a source of typical mistakes. If you want to count you need a quantity like: a piece or a bit of or some information because is like water or coffee needs to be in quantities. The United States is one country so it takes a singular verb: the United States, the Netherlands is (not are) although the two words are in plural. Mathematics is (not are), the news is (not are) but my glasses are broken. In addition the word is ambiguous. It can refer to glasses used by people who are short-sighted or as the plural of glass
The French seem to have some problems with numbers shown in their complicated and long way of saying for example "ninety" "quatre vingt-dix" literally "four twenties and ten". In English all of a sudden we have eleven and twelve but the teens start from thirteen whereas from twenty on the system remains the stable. The orthography is even more complicated. In the word <four> there is a /u/ but not in <forty>. The word is written differently from . There are many words in English for zero depending upon usage: o (h) BE for phone number or bank account number, zero for temperature, nought for mathematics, nil in football and love in tennis. The word love is said to come from French. The French word for the egg is l’oef. This word sound to the English ears like love and because it looks like an o (h) it is used in tennis. The word null is used in expressions like null and void.
Some words can be countable and uncountable at the same time: For example business: we do business. (Uncountable). These businesses (industries) are important (countable). Protein behaves in the same way 1) there aren't many proteins vs. 2) There isn't much protein 1) means that there aren't many different kinds of proteins. Let's say only protein A and B, but you can have a ton of each. 2) Means that the total amount of protein (regardless of variety) is low, i.e. you can have proteins A through Z but the total amount is little. What about 1 spoonful or 2 spoonfuls? Or spoons-full. Most uncountable' ouns can be used in the plural in some contexts. Is it more helpful to think of countable/uncountable as characteristics rather than categories? Plural forms of different drinks or proper names add to the problem.
In business people use the word figure instead of number. The sales figures have increased. A written or printed symbol representing something other than a letter, especially a number is a figure. So, a figure could be a number, e.g. 1000, or a symbol, e.g.'pi'. Perhaps when we are referring to the sign, the amount as a whole, we use figure, whereas we use number to refer purely to the number. Tricky! It could be collocation! We say sales figures, but not sales number. Is figure a digit and has to do with fingers (0 to 9)? Maybe a number is a mark on a scale written in figures. When you speak of some amount, not order, we say 'figures'.
When words are uncountable we need to use quantities to make them countable: a bag of, a drop of, a pair of, a glass of, a cup of, a dozen,...To make this confusion even worse we have different plural forms: Car...cars; man...men, woman...women; child...children; wife...wives; tomato...tomatoes; goose...geese, foot...feet; oasis...oases, crisis…crises; mother-in-law...mothers-in-law; baby...babies; boy...boys.
Some words don’t have a plural form or the plural is the same as the singular: one hovercraft, two hovercraft, one fish, two fish but fishes in a restaurant as a dish. Series and species are the same in singular and plural. Some like the letters of the alphabet and abbreviations take an apostrophe + s =‘s: 1960’s, MP’s
Numbers go before adjectives: six lazy daisies. Some nouns are difficult to pronounce: cloths and clothes. Some singular verbs take plural complements: The biggest timewaster is meetings but three thousand pounds is a big sum of money. In some countries phone numbers are given in pairs of numbers while in England it's number by number e.g. 245688 In England, "Two- four- five- six, double eight", but in Spain or Germany, for example, "Twenty-four, fifty-six, eighty-eight". I don't know the conventions for other English-speaking countries.