How to Creating Individual & Corporate Accounts, with Different number range

Hi Experts,

We have  a Requirement for our client.

Here Sales Representatives are creating the Account's like Individual and corporate, So the client need's the number range as different for both accounts.

Like Example

Individual accounts:   they need  100000 to 700000

Corporate accounts: they need 800000 to 1000000

Once the Sales Representative creating the individual account from web UI  it has to take the number from 100000 to 700000. and the same way if creating corporate account then it will pick 800000 to 1000000.

Could you Please Guide me on this how can we do this?

Regards

mohammad