The topic Operations on Whole Numbers primarily concentrates on the operations that can be performed on whole numbers. Whole numbers follow the commutative and associative property of addition. Every whole number has additive and multiplicative identity too. The sum of two even and odd numbers is considered as an even number.
A magic square can be considered an application of whole numbers. A magic square has the same number of rows and columns, and the sum of numbers in every row, column and diagonal is equal. Further, the result of the subtraction can be checked by adding the result with the second addend to get the first addend as an answer. Whole numbers also follow the commutative property of multiplication. Therefore, the distributivity of multiplication over addition and subtraction of whole numbers can be used to calculate the product of two whole numbers.
Chapter 4 Operations on Whole Numbers further discusses checking the divisibility of whole numbers. It can be verified by proceeding with actual division and noting down the quotient and remainder. Substitute those in the formula, "Dividend=Divisor * Quotient + Remainder" to get the actual dividend. There also exists a whole number a where a/a=a.
The chapter also mentions that the following rule can remember the square and triangular numbers,
Nth square number= n*n and Nth triangular number= n*(n+1)/2.
Various patterns can be identified and extended using these square and triangular methods.