The Common Core State Standards teach students the algorithm for multi-digit addition and subtraction in 4th grade. But some experts say it should be taught sooner.

The present paper describes the success, the methods (mental, informal written, standard algorithm) and the strategies of informal written arithmetic to be observed when 300 elementary students worked ...

This study analyzed children's use of mental computation strategies and the standard algorithm on multi-digit subtractions. Fifty-eight Flemish 4th graders of varying mathematical achievement level ...