You might have seen the following "viral" maths problem on social media at some point:

• A book costs £1 plus half its price. What does it cost?

Hopefully your answer isn't £1.50...

I got thinking about how you could make the problem a bit more challenging. Here's one idea I had:

• A book costs £1 plus half of (£1 plus half of (£1 plus half of (£1 plus half of... (£1 plus half its price)))))))))))))))))))))))). What does it cost?

(For reference, there are 24 sets of brackets.)

If you manage to solve this, I'd love to hear your suggestions for how to spice up the original problem!