Australia's Number System: The Universal Decimal (Base-10)

Australia uses the **exact same number system as almost the entire world: the Hindu-Arabic Decimal (Base-10) System**.

What This Means

• Digits: **0, 1, 2, 3, 4, 5, 6, 7, 8, 9**.
• Place Value: Each position represents a **power of 10** (units, tens, hundreds, thousands...).
• Example: **1,234** = (1 × 10³) + (2 × 10²) + (3 × 10¹) + (4 × 10⁰).
• Decimal Separator: **Dot/Point (.)** – e.g., **3.14** (not comma).
• Thousands Separator: **Space or Comma (,)** – e.g., **1 000 000** or **1,000,000**. (SI standard prefers space).

Measurement = Metric (SI)

Since **1970s metrification**, Australia uses **exclusively metric units**:

• Length: **mm, cm, m, km**
• Mass: **mg, g, kg, tonne**
• Volume: **mL, L, kL**
• Temp: **°Celsius**
• Area: **m², ha, km²**

Indigenous Number Systems (Historical/Cultural)

Pre-colonization, **250+ Aboriginal language groups** had **diverse counting systems**:

• Many: **Base-5 (quinary)** or **Base-20 (vigesimal)** cycles.
• Some: **Body-part tallying** (fingers, wrists, elbows, shoulders, head).
• Concepts of **"mob" (group) quantity** often sufficed; exact large numbers less critical than relational/ecological knowledge.

Today, **all official, educational, commercial, and scientific use in Australia is Decimal/Metric**. Indigenous mathematical knowledge is increasingly recognized in curricula.