Doing quick calculations without writing anything down can seem tricky, but with the right mental math techniques, students ...

Ellis showed a subtraction problem, performed both using the traditional regrouping, or borrow-and-carry, algorithm and using an example from the common core. Here’s a screenshot of the two methods.

Julia begins with a Number of the Day warm up activity, followed by practicing 2 and 3 addition and subtraction equations, with and without regrouping, using base 10 drawings, expanded from ...

Column addition and subtraction. In the column method of addition and subtraction, numbers are written so their place values line up vertically forming columns for ones, tens, hundreds, thousands etc.

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.