Don’t fret over not being able to make that simple calculation. Just reach out to a nearest calculator app.
If you hear the words ‘Google spoiled you’ because you don’t blink twice before answering a question via Google, ignore them.
Your memory needs to hold thoughts and dreams, not formulae and places.
Side Note: Your brain is waiting to create something more significant. ‘WOW’ is in what you can create, not what you can memorize (or the act of memorizing).