The common-core math standards require that students learn the standard algorithm for multi-digit adding and subtracting—you know, the process in which you line the numbers up vertically to add or ...

When you are solving an addition calculation with a two-digit number, you need to think about tens and ones. A place value chart can help you to see the value of each digit in a number. For example, ...

Join Mrs. McCartney for an addition number talk with D.C.! Join Mrs. McCartney for an addition number talk with D.C.! Get ready to have some fun subtracting two-digit numbers with regrouping and ...