**A**digits, with numbers going straight from

**9**to

**10**.

Each digit represents a power of **A**, rather than a power of **10** so, for example, **234** represents **2*****A*****A** + **3*****A** + **4** = **C8** + **1E** + **4** = **EA**. Similarly, **42** represents the number **2A**.

With practice, calculation can be done without converting back to hex first.