Happy (almost) grad season! But that can be high school, post-secondary or lots of us adults graduating to financial adulthood. While 2+2=4 may sound simple enough, it’s not as much of a math example, as a reminder to use basic common sense. It’s actually a huge poster in the office of a Wall Street investment guru.

In other words: if it doesn’t add up, be careful, because there’s something wrong. But how many times do people not stop to think before investing, before borrowing, or making some really bad financial decisions? Here’s are some really common ones:

You can borrow your way to wealth. Sorry, no matter how great the rate, borrowing is debt and that’s the total opposite of building wealth.

You have received an inheritance of $25 million from a distant relative if you just send some money up front to Nigeria. Come on…get real…

I don’t need to start saving for retirement for few years. Ah, the common sense of delaying. If you’re 20, $9,300 will turn to a million at retirement. If you wait until 45, you’ll need $150,000. If you wait until 55, you’ll need almost $400,000. So if you agree that 2 + 2 = 4, are the odds better you can save $9,300 or $150,000 to $400,000?

Leasing a vehicle. You pay for three or four years and then just return. All those years of payments and you’re taking the bus home or starting another car rental cycle.

An internet start-up company email tip. Their stock tripled or more within months, with no earnings, and in business less than a year or so. It’s now ready for the crash… as soon as you invest.

Trying to outsmart the entire investment world by jumping in and out of investments. Computers sell billions of dollars of stock trades a day and try to gain one-tenth of a second on one another. But you think you can do it for an hour or so with information that’ll be hours old. That’s why day traders lose money 93% of the time.

You have a chance to get in on a 20% investment return. OK, parking your money at the bank gets you around half a percent. Does 2 + 2 equal 4 when someone is promising you 40 times a safe return?

Many ads for a ton of products or services promise something for nothing. Does that seem logical? Does that add up? The weight loss industry advertises like crazy in January for your New Year’s resolutions and now for bathing suit season with all kinds of promises…in a business with a 99% failure rate.

Maybe our formal schooling has stopped, but the learning can never ever end, or you’re in big trouble growing your career, just as much as your money.