Mr Gregg tweeted an image of this and got a reply that took it further:
@Simon_Gregg good one! You can propose a latin square with no colour repetition on the diagonalsSo... diagonals...
— Daniel Ruiz Aguilera (@druizaguilera) June 26, 2014
We used a Word document (switching the gridlines - 2cm - on, to snap to grid) as there aren't enough plastic squares for everyone to have a go!
Mr Gregg had had another tweet:
@tocamates @druizaguilera @Simon_Gregg we're talking diagonal squares here! Actually you can go MUCH further: http://t.co/jpK4ckkIALSo, now for something much harder.... Euler squares! (We've met Mr Euler before!)
— theoremoftheday (@theoremoftheday) June 26, 2014
Mr Gregg had made a Word document for this too. This time there are shapes and colours, and both have to be organised!
Mr Gregg said we wouldn't try for very long because it looked very hard! But, just as he said, "Right, that's enough," Rozenn shouted out, "I've done it!"
And she had - well done Rozenn!
A big thank you to all the people on twitter who helped us!
Mr Euler said it was not possible to make this kind of square if its size is 2, 6, 10, 14...
He was right about 2 and 6, but in 1960 it was discovered it is possible with 10 and all the others: