What do we call a symbol used to represent a number

Tcan be concluded that % of the seniors would prefer to see more candid pictures in this year's edition of the yearbook.

What is the area of the triangle 10 13 12

Jermaine has t subway tokens. karen has 4 more subway tokens than jermaine. raul has 5 fewer subway tokens than jermaine. which expression represents the ratio of karen's tokens to raul's tokens