Here is a confession – If anyone read my last blog post they will have seen a mistake with the question I posed at the end – If you are looking now, this has now been corrected!

The question asked to fill the second box in. The first box says x 2 , so if we feed in 6, the number in the middle is 12. So the second box needs to be an operation that gets from 12 to 6.

Without the clue now added, you could have at least two different answers. “Take 6” is what I expected, and with the clue that is now the RIGHT answer. Without the clue, ‘Divide by 2’ would have worked too.

(So would ‘add -6’ if we are getting pedantic, though really thats the same as subtract 6. Another possible answer would be ‘Raise to the power of 0.721, but I wouldn’t expect people studying Number machines to spot that. There are probably a lot of other operations that get from 16 to 6 in we go that deep!)