*Thank you to Rali, Shreya, Gracie and Avril Chloe for sending us their thoughts about the arrangements of coins in Circles, Circles.*

We have investigated building up triangles made of circles.

- Finding the meaning of the next size up
- Finding a pattern to get the next size up

Our definition for the next size up on a triangle is to add a border round the original triangle and to keep on doing it to get the additional size up.

The rule used is: multiply the triangle number by 9 then add the size/border number.

Algebraically it was:

n x 9 + n which is 9n + n which is 10 n.

Response to: