Goal

A number sequence with one missing. Work out the rule and pick the missing number — as many as you can in 60 seconds. After each answer the rule is shown, so a miss still teaches you something.

Levels

• 4 right at a level moves you up; 2 misses in a row move you down.
• Rules start with a steady step, then add multiplying, a step that grows, square numbers, two sequences taking turns, "the two before added", two steps in turn, and a step that doubles.
• From level 2 the gap can be anywhere — even first.

Scoring

A right answer earns 3 + the level, plus 1 for every 3 in a row (up to +3). A miss costs 2 + the level.

Inductive Reasoning

Finding a rule from a few examples is the heart of fluid intelligence — and the wrong options are the slips people really make, so you learn to check a rule against every number.