Your credit score holds a lot of power in your life.

Lenders use them to decide whether to loan you money, and in some cases, how much interest to charge you.

But here's the thing: It's not that easy to figure out exactly what score a lender is using, because you have more than just one. A lot more.

Earlier this month, the Consumer Financial Protection Bureau fined credit reporting agencies Equifax and TransUnion over claims they deceived people by saying the scores they sold to consumers were the same ones lenders use.

Problem is, that's not always the case.

"When you go from one business to another or one type of lender to another, they will likely use different scores," explained Rod Griffin, director of public education at credit reporting agency Experian.

Related: 6 steps to a better credit score

FICO scores, which tend to range from 300-850, are often considered to be the gold standard in credit reporting. There are 19 different kinds of FICO scores, with FICO Score 8 being the most widely used version. There are industry-specific scores that assess different risks, which means even within FICO, your scores can vary.

"We found about 10% of consumers have score differences of 100 points or more across FICO scores," said Ethan Dornhelm, vice president of scores and analytics at FICO.

There's also VantageScore, which also provides scores on a 300-850 scale, and is used by more than 2,400 lenders.

Your score is heavily determined by what's in your credit history, and you have three different credit reports that are maintained by the three national credit bureaus: TransUnion, Equifax and Experian. Since the information and scoring model in the three reports vary, each bureau can show a different credit score.

"There are literally billions of bits of data that are updated in credit reports every day," said Lynnette Khalfani-Cox, author of Perfect Credit.

Different lenders might even have their own version of your credit score.

FICO can create a customized score to tailor to a lender's needs to evaluate borrowers, while some lenders might use their own credit score models, explained Griffin. There are also "boutique scoring companies" that will create scores for lenders.

He estimated that consumers can have hundreds of credit scores.

Auto lenders might weigh various aspects of your credit history differently than a credit card issuer or mortgage lender. For instance, a credit card company might look more at your history with revolving credit while a car lender could focus more on your repayment record.

Insurance companies can also come up with their own credit scores as a way to evaluate things like a customer's likelihood to file a claim or pay a premium, according to Griffin.

Related: Should I open up a credit card in college?

So how do you know which score lenders will be looking at? Simply put, you don't.

Websites like Credit Karma and Credit Sesame provide free scores from the credit bureaus along with a breakdown of their information that can help consumers track their lending attractiveness.

Many credit card companies have also started to give customers free credit scores.

Credit expert Gerri Detweiler recommends consumers who are looking to get a mortgage purchase their scores directly from MYFico.com, while people looking to check their credit attractiveness in general are fine to use free services that provide their scores.

But you still won't know exactly what the lenders will review, which is why experts said the best thing you can do is keep paying your bills on time, limit the amount of credit you use and maintain a good mix of credit.

"If you take take care of your credit reports, your scores will take care of themselves," said Griffin.

To stay in the know about your credit history, experts recommend regularly reviewing your reports. Each credit bureau is required to provide customers with one free credit report a year, which means you could review your history every four months. You can review the free copies of the reports at annualcreditreport.com.

If you do get turned down for credit, federal law requires lenders detail which score was used and why an application wasn't approved. That's a good opportunity to pinpoint and work to improve any problems.