Ever had an argument with a colleague about the commas in a sentence like the following?   The battery pack gives you several options:  6 hours, 4 hours, 3 hours and 40 minutes, 2 hours and 45 minutes.  Is that four options or five options?  A comma before the last and makes it clear.   But do you ALWAYS need a comma before that last and?  Answer:  No, the serial comma is optional.  But you’re always safe to use it for clarity sake—as illustrated in the “battery-pack” sentence. Here are a couple tips to prevent grammar gaffes and save you a few minutes in reaching for a reference book: • The assure/insure/ensure dilemma:  (All three words mean to give a guarantee—but they aren’t interchangeable.) Use assure only when you’re referring to someone talking or writing.  Use insure only when … [Read more...]