Dear Liz: In a recent column you mentioned Social Security’s delayed retirement credit, writing that someone’s benefit could grow 32% by delaying benefits for four years between ages 66 and 70. Four years’ worth of accrued 8% increases in Social Security result in a cumulative increase of 36%, not 32%. I would think any financial planner would understand compound growth.

Answer: Social Security’s delayed retirement credits don’t compound.

Now, you may feel a little silly for pointing out an error that wasn’t actually an error, especially because you could have found the correct answer through a quick internet search (“Is Social Security’s delayed retirement credit compounded?”). But who hasn’t made a similar mistake? Sometimes what we don’t know about money isn’t the problem — it’s what we do know for sure that just isn’t true. (A similar quote is often attributed to Mark Twain, although there seems to be no evidence he ever said or wrote it.)

When I’ve made errors in this column, it’s often because I thought I understood something I didn’t or that my knowledge was up to date when it wasn’t. That’s why it’s so important to double-check our information with authoritative sources.