Question about converting datatypes

hey guys, so im going through ASDG, page by page, and learning everything from scratch. he’s explaining datatypes, i.e. strings, numbers, booleans, arrays, etc…i get that. then he goes into explaining how to convert datatypes from numbers to strings using “toString” , and then strings to numbers using “Number()”…and then later, strings to booleans and stuff. My question is this. could some one please explain to me a situation where someone would want to turn a number into a string or a string into a number?and how would someone even turn a string into a number? i dont understand how that works.