When number pyramids have a sequence on the bottom layer, some interesting patterns emerge...
Three people chose this as a favourite problem. It is the sort of problem that needs thinking time - but once the connection is made it gives access to many similar ideas.
Libby Jared helped to set up NRICH and this is one of her favourite problems. It's a problem suitable for a wide age range and best tackled practically.
Lyndon chose this as one of his favourite problems. It is accessible but needs some careful analysis of what is included and what is not. A systematic approach is really helpful.
NRICH has always had good solutions from Madras College in St Andrew's, Scotland but the solutions to this problem were truly exceptional.
A new problem posed by Lyndon Baker who has devised many NRICH problems over the years.
Nick Lord says "This problem encapsulates for me the best features of the NRICH collection."
Go to last month's problems to see more solutions.
Professor Korner has generously supported school mathematics for more than 30 years and has been a good friend to NRICH since it started.
Can you beat the computer in the challenging strategy game?
A Sudoku with clues as ratios.