# Tag Archives: common denominator

So you think you HAVE to find a common denominator when adding fractions? Well, not really. Especially if you want to inspire kids to really think like a mathematician and do some inventing! Continue Reading →

### LCM and GCF – And Something Really Cool

In a previous post, we learned that you don’t have to use a LCM (least common multiple) to find a common denominator to add fractions. In another post, we learned that you can use primes instead of the GCF (greatest common factor) to reduce fractions. And now I’m going to demonstrate that finding the LCM… Continue Reading →

### Adding Fractions: Why Avoiding Common Denominators Works

I wrote this post showing that adding fractions can be done using the algebraic definition of addition of rationals: MathHeadInc (via twitter) has requested a video showing why this works. I aim to please. Here is the video showing why adding fractions using a common denominator is the same as the definition of addition of… Continue Reading →

### How to Never Find a Common Denominator Again

Do you keep struggling to teach common denominators? Do your kids just not “get it”? Well, it’s time to quit. Yep! You can teach (and do) fractions without ever finding a common denominator. The key is in the definition of addition for rational numbers. If you have two numbers  and  the sum of them is . Granted… Continue Reading →