😳 It could be "1" too.

Not only "25".

Depends if you go clockwise or otherwise.

Start with 4 and multiply with the middle 5

-> put result in segment on the other side

... then 3 and multiply with the middle 5

-> put result in segment on the other side

...

or clockwise:

Start with 10 and divide by the middle 5

-> put result in segment on the other side

... then 15 and divide by the middle 5

-> put result in segment on the other side

...