As he snapped the "Dorofeev & Peterson" book shut, the spiral on the cover didn't look so daunting anymore. Sasha packed his bag, ready for the morning's lesson, knowing that even if he got a decimal point wrong, he’d survived another round with the most famous math duo in the fifth grade.

"Just three problems," Sasha whispered, looking at the familiar spiral patterns on the cover. But in a Peterson textbook, "three problems" usually meant ten sub-questions that required the logic of a chess grandmaster. The First Hurdle: The Number Pyramid

The second problem was a classic Peterson "motion" problem: two cyclists leaving Point A and Point B at different times. Sasha drew a diagram, a messy line with arrows pointing everywhere. He could almost hear his teacher's voice: "Don't forget the units, Sasha!" He converted meters per minute to kilometers per hour, his tongue poking out in concentration. When the two cyclists finally "met" at exactly 12:45 PM in his calculations, he felt a surge of victory. The Final Boss: The Logical Riddle