Pattern Recognition: Series and Sequences

Series questions hide a rule; your job is systematic search, not staring. Professionals check a mental list of rule families in order.

Key Concepts

• Check differences first: constant? growing? alternating? (2,6,12,20 → differences 4,6,8)
• Then ratios (geometric), then squares/cubes proximity, then alternating dual series
• Figure series: track one element at a time — rotation, count, shading, position
• Two interleaved series is the classic trap: check odd and even positions separately
• Write the differences down; working memory lies under pressure

Try It Yourself

Solve daily: 4, 9, 19, 39, ... and 5, 6, 8, 11, 15, ... Write the rule for each before checking (double+1; growing differences).