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 ...

Multiplication and division are connected. Think about the times table facts you have been learning. 3 'multiplied by' 7 makes 21. 7 'times' 3 equals 21. The inverse operation is division. 21 'shared ...

Subtracting larger numbers in your head is not always easy, so you can use the column method to take one number away from another. You write the larger number above the smaller number, so that the ...