Am I completely stupid?????

Good morning, I hope all have slept well?? I certainly have not
And believe me I am not stretching the truth!
My problem (although its not really a problem! It’s just bugging me)
How on earth do you work out how many vertical stripes
To put on your cake?? This has been running through
My head for the majority of the night and I have scoured the net this
Morning!! Is it mathematical? Because if it is then I am so
Never going to do it. Somebody PLEASE help me Work this
One out….. And then I can snooze! ;) happy baking xx