You may use any numbering scheme you wish but most accountants suggest you use a scheme which organizes the Chart of Accounts in a logical manner and which groups account types by broad number segments. The most common method of doing this is to number assets starting with 100 or 1000. Liabilities would start with 200 or 2000, Owner Equity (or Capital) 300 or 3000, Income 400 or 4000, Expenses 500 or 5000. In this case you should use the even hundred or thousand for the Title Accounts. (1000 ASSETS, 2000 LIABILITIES, 3000 EQUITY, etc.) This method forces you organize your Chart of Accounts in the logical manner described above.
Whether you number using hundreds or thousands is a matter of choice and what fits your business size best. If you have a relatively few accounts numbering using hundreds may suffice. Larger numbers of accounts should use thousands.
Usually you will leave a few slots open between each account number (for example, number successive accounts by incrementing each number by 5, e.g. 105, 110, 115, etc.) so you have room to add new accounts as needed in the future and still maintain the numbering scheme. You should also name the accounts in alphabetical order wherever possible if consistent with your numbering scheme.