I'm a bit of an a$$ in this regard. I do the following:
-Give a set of ordinary bookkeeping tasks and have them classify them as they would in software
-Fictitious bank account reconciliation
-If a balance is off by an immaterial amount, (and for sake of the "test") how long do they spend trying to sort it out before they ask me about it?
-Identify normal balances (debit or credit) for various G/L accounts
-Create basic P&L and balance sheet from a basic trial balance
-Prove basic math skills, such as the aforementioned days in a month (February being an exception depending on year), and converting percentages to decimals
-Throw in a few transactions not found in every business to determine if they can figure out appropriate treatment, or if they completely fail. They are not difficult, but may include inventory topics, posting depreciation/amortization, etc.
Can't pass 100%? I do not hire. 100%? I'll consider them for hire. I have had people with former CPA credentials that could not perform these simple tasks!