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Module_03 // Physics of Math

NUMBER PROPERTIES

If PEMDAS is the grammar of math, Properties are the physical laws. They tell us exactly how we can stretch, swap, and reshape an equation without breaking it.

Commutative Property

The word "commute" means to move around. This property says you can swap the order of numbers and get the same answer.

a + b = b + a
⚠ Only works for (+) and (×).

Associative Property

Who you "associate" with means who you group with. This property lets you move the parentheses to group numbers differently.

(a + b) + c=a + (b + c)
⚠ Only works for (+) and (×).

Identity Property

Every number wants to protect its identity! These rules tell us what we can add or multiply to leave a number completely unchanged.

Additive
a + 0 = a
Multiplicative
a × 1 = a
Interactive Lab

The Distributive Property

This is arguably the most powerful tool in Algebra. To multiply a number by a group, you must "distribute" that multiplier to every single item inside the parentheses. Use the Area Model below to prove why this works!

Distributive Area Model

A (Multiplier / Height)4
B (First Inner Term)5
C (Second Inner Term)3
Algebraic Proof
4(5 + 3)
4×5+4×3
20+12=32
4
5
20
3
12
Width = 8

Verification Protocol

Knowledge Check: Properties of Math1 / 3

Which property is demonstrated by this equation: 4 × (3 + 5) = (4 × 3) + (4 × 5)?

Rule Mastery

You know the laws of mathematical motion.

Next: Ratios & Proportions