Please explain to the class what it means to:1.Rewrite a number to a different baseAdd two or three numbers to a different baseSubtract two numbers in a different baseWhy do we learn to work with...

Please explain to the class what it means to:1.Rewrite a number to a different baseAdd two or three numbers to a different baseSubtract two numbers in a different baseWhy do we learn to work with numbers in different bases?
2.Please provide examples of your answers.