Question

For any whole numbers a, b, c, is it true that (a + b) + c = a + (c + b)? Give reasons.

Answer 1

For any whole numbers a, b and c, we have:
(a + b) + c = a + ( b + c​) 
Let a = 2, b = 3 and c = 4 [we can take any values for a, b and c]
LHS = (a + b​) + c
= (2 + 3) + 4
= 5 + 4
= 9
RHS = a +(c + b)
= a + (b + c) [∵ Whole numbers follow the commutative law]
= 2 + (3 + 4)
= 2 + 7
= 9

∴ This shows that associativity (in addition) is one of the properties of whole numbers.