Solved IB ACIO Question
A solved IB ACIO PYQ — decoded step-by-step.
Solve it the standard way once — then learn the shortcut.
Q · Series (Numeric and Alphanumeric)medium · 45s
What is the missing number: 6, 11, 21, 41, 81, ...?
TopicSeries (Numeric and Alphanumeric)
Question Typemultiple choice
Difficultymedium
Marking+1 / −0.25
Test Duration30 min
Step-by-Step Solution
The complete worked solution.
Every step explained — no skipped algebra.
Each term approximately doubles and subtracts 1.
Final Answer: Option C — 161