There aren't many lawyers who went into law because a career in theoretical mathematics would have been just too easy. In fact, many of us can probably get away with counting on our fingers much of the time -- except when it comes complex patent litigation. Or to client funds. Lawyers' ethical responsibility to maintain a client's funds in trust is one of the most common reasons lawyers face disciplinary action.
As a rule of thumb, you should strive to manage your client funds so that, should you die tonight, everything would remain in order. Of course, we don't always live up to that ideal. So, if you find an accounting mistake in an trust account, what sort of ethical issues might arise and what must you do about it?