VTMO 2026 - Grade 7 - Final - SET 5 - Self-study Question 5

a) Can the numbers $1,2,3,\ldots,100$ be arranged in a line so that every adjacent pair $a,b$ satisfies $|a-b|=2$, or $a\div b=2$, or $b\div a=2$?

b) Answer the same question for an arrangement around a circle.