Addition and Subtraction of Whole numbers

The two numbers can be added in columns by placing them one beneath the other such that their place values are aligned

To check if the result of addition is correct, rearrange the numbers and add them again. If the sum of the two numbers come out to be the same irrespective of the order, then the sum is correct

The two numbers can be subtracted in columns by placing them one beneath the other such that their place values are aligned

The minuend is the number from which the other number is subtracted. It is generally the bigger number.
The subtrahend is the number which is to be subtracted. It is generally the smaller number.
The result obtained after subtracting the two numbers is called the difference

The order of the numbers in subtraction is important, that is the minuend should always be placed on the top and the subtrahend below the minuend

To check if the result of subtraction is correct , add the subtrahend to the difference obtained.
If their sum yields the minuend, the answer is correct

Addition and subtraction are inverse operations

We can "undo" an addition by subtracting the addend from the sum. For example: 5 + 6 = 11 is an addition fact. It can be undone by subtraction, that is 11 - 6 = 5

We can "undo" a subtraction by adding the subtrahend to the difference of the two numbers. For example
11 - 6 = 5 is a subtraction fact. It can be undone by an addition operation, that is  5 + 6 = 11