There’s a single three-digit number that plays a crucial role throughout your life. This number, your credit score, is relevant in many areas, but nowhere is it more important than in taking out a loan, including a mortgage. The relationship is simple: The higher your credit score, the lower your interest rate. The reasoning makes sense: a good credit score tells lenders that you're financially responsible, so you'll likely stay current on your payments. This makes you a lower risk for them....