Now, he solves for an unknown in any position. This video addresses Common Core Grade 2 Standard Operations & Algebraic Thinking: Represent and solve problems involving addition and subtraction.

KS2 Maths. Maths Challenge 1. Ralph and Matrix have another mental maths quiz and this time the focus is adding and subtracting 9. BBC School Radio. BBC Teach.

In this KS2 Maths article you'll find out how to use mental methods when doing addition and subtraction in your head. We also have KS2 Maths videos, a quiz and lots of examples.

Under the common core, there are many ways to do subtraction—none of which involve borrowing and carrying.

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.