Students go over addition and subtraction with regrouping using different strategies. In this lesson, students go over addition and subtraction with regrouping using different strategies to solve.

The 2nd grade standards require students to “fluently add and subtract within 20 using mental strategies” (CCSS.MATH.CONTENT.2.OA.B.2). So while the strategies may take longer at first—even ...

There are lots of different tools that help you to do mental addition and subtraction. Remember, it doesn't have to be done entirely in your head, you can still use a pencil and paper to help.

Very impressive, Albert. Rounding numbers to the nearest 1, 10 or 100 can help with lots of mental maths problems. To add 9 to another number, add 10 and then subtract 1: 36 + 9 = 36 + 10 - 1 = 45 ...

and we'll use 10 to add and subtract. Let's warm up our math brain with a mystery math mistake. Oh no, all of our Math Mights have gotten their strategies all mixed up. D.C. is holding onto ...

In fourth grade, students focus most on using all four operations - addition, subtraction, multiplication, and division - to solve multi-step word problems involving multi-digit numbers.