For third graders learning Common Core math in Georgia, there are four ways to subtract—and only four ways allowed.

If you can subtract two 3-digit numbers from each other, then you can use the same method to subtract two 4-digit numbers. You use the same method, no matter how many digits are in the numbers.

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. Fourth ...

Find out about the column method to subtract more than 4-digit numbers with this Year 5 article from BBC Bitesize.