If you attend and finish the school at babypips.com you would be familiar with the lesson talking about this:

"A carry trade involves borrowing or selling a financial instrument with a low interest rate, then using it to purchase a financial instrument with a higher interest rate. While you are paying the low interest rate on the financial instrument you borrowed/sold, you are collecting higher interest on the financial instrument you purchased. Thus your profit is the money you collect from the interest rate differential. For example:

Let’s say you go to a bank and borrow \$10,000. Their lending fee is 1% of the \$10,000 every year. With that borrowed money, you turn around and purchase a \$10,000 bond that pays 5% a year.

Anyone?

You got it! It’s 4% a year! The difference between interest rates! "

The best part is not only about the percentage you earn, but also the leverage you use to earn those interest.
If you have \$100,000 and you put in the bank for 1 year at 5% interest you would earn \$5000 1 year.
But if you carry trade and trade with 10:1 leverage putting in the bank \$1,000,000 instead of \$100,000, you earn \$50,000 instead of only \$5000.
But beware of using leverage too much because whatever brings tremendous profits also could bring tremendous loss. Happy trading!

I found this for “interest calculations”: