PRACTICE
Understand first, then try it yourself.
Study trainer
205 original practice problems across all 12 chapters. Hints open progressively; viewing a solution does not count as mastery.
Open trainer →Interactive demonstrations
Example · n from 1 to 40
Factor pairs
1 × 122 × 63 × 44 × 36 × 212 × 1
Composite
A highlighted pair has two integer factors greater than 1. Such a pair proves compositeness.