First of all, there are always 1's along the sides...

To get the other numbers, we add the two numbers that are above... For example, we added 1 + 1 to get the 2 and we added 1 + 3 to get the 4. Can you see that this is happening everywhere?

So, what goes in the red blank?

What's the next line?

And we can keep going and going and going!

When you get into your Intermediate Algebra class, you'll see lots of ways that this cool triangle can be used!