This big box adds something to any number that goes into it. If you know the numbers that come out, what addition might be going on in the box?
Jenny Murray describes how she developed her interest in making and breaking codes.
From group 3, ict 2 pere at Olongapo City National High School, Ict in the Philippines, we had the following picture as a suggestion for the completion.
We had, from Harry at Stonebroom, the following:
I think that every side will have a triangle to make it a star
and from Ayesha from Gag in Pakistan we received this similar suggestion:
On the plan side we will add a triangle because it will be in the same form
from every side