Automatically generate a unique 'order number'

[twinklep]

Hi, How do I automatically have a order number/purchase order number gernerated ? This will make it easy for the retailer and clint to keep track of orders and will avoid duplication of orders.

[fridgemags]

The order number should be automatically generated in sequence.

such as

if the last order was 179
the next order would be number 180
181, 182, 183

and so on.

[twinklep]

Hi where do I set this option ? as my email confirmation does not give me any order #.