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If ABC goes to ABD....

Where do Ideas come from? This puzzle gives a clue.

When we have ideas, where do they come from?  There’s a puzzle that gives a clue.  Unusually for puzzles, this one has no wrong answers, so whatever answer you come up with will be fine.  Here it is:

If ABC goes to ABD then what does XYZ go to?

Think of an answer (any answer!) now, before you read ahead

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I've posed this question to hundreds of people over the years, and the majority - maybe as many as 70% of them - come up with the same answer.  Were you one of the majority whose first idea was: XYA?

Why is it that most people come up with XYA first?

It’s almost certainly because of our experience of a pattern of things going in cycles. When a clock gets to 12, it goes back to 1 again. Many people apply this same cyclic pattern to letters: since Z is the last letter, then why not go back to A and start again?

There’s nothing wrong with this answer, but it’s not the only one you could have come up with.  There are plenty of other patterns in life that you could draw from.  For example when you get to the top of a staircase you don't go back to the bottom again.

Here are some other answers that people offer as their first suggestion:






Some of these answers might strike you as creative, others odd or just weak.

The person who suggested XY1 felt that after the letters come the numbers. The XY person reckoned that since nothing follows Z, it should be a blank, while XYD decided that the rule was always “replace the last letter with D”. (That one felt a bit clunky to me, but it was genuinely their first thought on what the rule was.) The person who said WYZ thought that if the right-hand letter Z is unable to move “outwards”, then the left-hand letter, X, must bounce “inwards” instead to become W.

And what about the answer XYAA? How did this mould-breaking person come up with the idea of adding a fourth letter?

As it happens, the woman who gave me the answer XYAA is an accountant, and she thought it was the “obvious” answer. She uses a spreadsheet every day, and the column after Z in a spreadsheet is AA. When I asked her what she thought about the answer XYA instead, she said, “Oh, I do like that – who thought of that one?”

You may not have thought of her idea, but nor would she have thought of yours. New ideas sometimes depend simply on having a different experience, and hence different patterns to draw from.

The example of XYAA shows that when it comes to having ideas, two heads can be much better than one.


My book Any Ideas? is about the process and pitfalls of having ideas - on your own and with other people.