Choose the rule that matches your job.
The math becomes easier once you answer one question: does changing the order create a new result?
Combination
Order does not matter
For teams, pairs, or selections, A + B is the same group as B + A.
AB, AC, BCPermutation
Order matters
For codes, rankings, or sequences, A + B and B + A are different.
AB, BA, AC, CA, BC, CBWhat “allow repeats” changes
Without repeats, an input item can appear only once inside each result. With repeats enabled, results such as A + A become valid. This can increase the result count dramatically.
Why the generator may sample
Result spaces grow faster than they look. Rendering millions of rows can exhaust browser memory. The tool calculates the exact size first, then uses a safe display limit or random sample.