Hallo James,

6502 is a microprocessor, having a much smaller instruction set than Z80, e.g. Nevertheless due to very efficient addressing modes and special zero page instructions, program execution is rather fast. Instead of having many internal registers like Z80, 6502 uses external RAM and zero page addressing for fast accessing 256bytes.
6502 has no math instructions, but I remember that home computers consisting of 6502, like apple IIe, had rather fast mathematical algorithms, just because of using fast zero page addressing.
But having instructions for mulitplication or even division leads to even faster algorithmns, of course.

Bye,
Kai