A challenging optical illusion tests your observation skills by hiding the number 33 within a grid of 66s and 88s, all within a strict 7-second time limit. This exercise sharpens focus, attention to detail, and mental speed, proving how easily the brain can overlook subtle differences when relying on patterns.source https://timesofindia.indiatimes.com/life-style/health-fitness/de-stress/optical-illusion-challenge-can-you-spot-the-hidden-33-among-66s-and-88s-in-7-seconds/articleshow/125364565.cms