Question 11
Odd numbers are whole numbers not divisible by 2, for example 1,3,5,7,9,11,13,15,17,… . Initially 20 students stand in a row and are numbered 1,2,3,… from left to right. Students with odd numbers sit down. The students still standing are renumbered 1,2,3,… in the same order, and again those with odd numbers sit. This continues until Roy is the only student standing. What number was Roy assigned at the start?