### Video Transcript

Daniel is making dots that look
like triangles: one dot, three dots, six dots, 10 dots: add two, add three, add
four. The rule for the next number of
dots to use is add one more dot than you added before. How many dots will be in the next
triangle?

The question tells us there are 10
dots in the last triangle. We have to work out how many dots
would be in the next triangle. The question also tells us we need
to add one more dot each time. First, we added two. Then we added three. Next, we added four. So then we need to add five. Five is one more than four. 10 plus five is 15, so there will
be 15 dots in the next triangle.