How do symbols, words and numbers in English become plural?

■ How do symbols or words change? For some symbols or words, if they need to be used as nouns in some special contexts and need plural forms, you can add -s or -'s at the end of the words, for example, all -' s should be changed to+'s. All positive signs should be changed to negative signs. His speech was interrupted by annoying "ah" and "good" His argument contains too many ifs and buts. His argument contains too many ifs and buts. ■ You can add -s or-at the end of the number. For example, your 3 (') looks like 8 (') and your 3 looks like 8. However, if it is a number such as one, two, three or four, the general rule becomes plural. They arrived in twos and threes. They came in twos and threes. ~