3.2. MULTIPLICATION AND DIVISION
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An alternative version of (3) is:
(4) Tree Diagram Approach
2⇥3=6
Properties of Whole Number Multiplication:
(1) Closure Property
The product of two whole numbers is a whole number.
Example. The set of odd whole numbers and the set of even whole numbers
are both closed under multiplication, but the set
A = {3, 8, 13, 18, 23, 28, . . . }
is not closed since 3 · 8 2
/ A.
Commutative Property
Let a and b be any whole numbers. Then
ab = ba.