It seems some college students need to work on their reading comprehension. Or their vocabulary. Whatever the problem is, some students aren't grasping the concept of loans: 17% of first-year students who have federal student loans responded to a survey saying they had no student debt, according to a Brookings Institution report.

There are scores of stories and reports about the difficulty borrowers have repaying education debt, and that’s a serious issue, but the statistics about borrowers’ understanding of their loans and the cost of college are much more troubling.

The report from Brookings “Are College Students Borrowing Blindly?” cites some shocking figures, based on two data sets. The first, a survey conducted in spring 2014, included responses from first-time, full-time freshmen who applied for financial aid at their college, a “selective four-year public university in the northeastern U.S.” The second is the most recent result of the National Postsecondary Student Aid Study, a nationally representative analysis of first-year, full-time undergraduates with federal loan information available in the National Student Loan Data System.

The data reveals that students are generally clueless about the costs of higher education and how they’re paying for it. Nearly half of students underestimated their debt loads by at least $1,000, with 25% of students underestimating their debt by $5,000 or more.

I’m in Debt? Really?

There are a lot of reasons students may not fully understand their student loan debt: Students may be confused about the different kinds of loans (like federal or private), their parents may have taken charge of figuring out their education expenses, they’re simply not keeping track of their finances, or they really don’t understand the fact that borrowed money must be repaid. There’s not really a good excuse, considering the students had to sign paperwork saying they’ll repay the loan as agreed.

The gap between perceived and actual student debt is potentially more troubling than the growing student debt load itself. Failing to understand the costs of college and how you’re paying for it sets students up for an unpleasant reality check and regret if they can’t afford the debt they incurred along their chosen career path.

Student loans are rarely discharged in bankruptcy, and failing to repay them has serious consequences on the rest of your financial life. Missing loan payments is one of the worst things you can do to your credit, and if you default on student loans, you may face wage garnishment and calls from debt collectors.

Consequently, a low credit score can leave you unable to secure other forms of credit at affordable interest rates, not to mention rent an apartment or get a job. To see how student loans and your other financial behaviors affect your credit score, you can review two of your credit scores for free every 30 days on Credit.com.

Ideally, you’re well prepared to handle your student loans when you enter repayment, but if you think your loan payments will be unaffordable, you have a few options. If you have federal student loans, you may qualify for a variety of student loan repayment and forgiveness options. If you have private loans, you may be able to refinance. At the very least, you should reach out to your student loan servicer to see if there’s any way to avoid defaulting on your education debt.

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This article originally appeared on Credit.com.