Calculating total price in a form

I make a form to send by e-mail asking booksellers to put prices for some books in the text input fields. I hope that all value entered in input/name=book1 + input/name=book2 + input/name=book3 (type=text) should be send to my e-mail address as the same form, now with the text input fields filled with the value given by booksellers. So it should be nice too, if a can put the total price of all books as a value in another input/type=text. thanks for any help a. -- Adagilson Batista Bispo da Silva Bibliotecário FIOCRUZ-Centro de Pesquisa Aggeu Magalhães Fone 81 3302-6524