**Whole numbers** are the set of positive integers. They do not have any decimal or fractional part.

**Natural numbers** along with zero(0) are whole numbers.

**Addition of whole numbers** always gives a whole number. Thus whole numbers are closed under addition.

Eg. 5+7 = 12

**Subtraction of whole numbers** does not always give a whole number. Thus whole numbers are not closed under subtraction.

Eg. 5-7 = -2, which is a negative integer and not a whole number.

**Multiplication of whole numbers** always gives a whole number. Thus whole numbers are closed under multiplication.

Eg. 5x7 = 35

**Dividing a whole number** by another does not always give a whole number. Thus whole numbers are not closed under division.

Eg. 5÷7 = a fraction, thus it will not be a whole number.