Inclusion-Exclusion Calculator
Use inclusion-exclusion to count the union of two or three overlapping sets. This educational calculator shows the result, explains the rule, and gives step-by-step reasoning.
Calculator
What this calculator teaches
Use inclusion-exclusion to count the union of two or three overlapping sets.
Discrete mathematics is the foundation for logic, algorithms, data structures, graphs, combinatorics, and many computer-science topics. These calculators are designed to support learning rather than replace reasoning.
Formula & Symbols
| Concept | Formula or rule |
|---|---|
| Two sets | |A ∪ B| = |A| + |B| − |A ∩ B| |
| Three sets | |A ∪ B ∪ C| = |A|+|B|+|C|−|AB|−|AC|−|BC|+|ABC| |
Worked Example
- Keep the default inputs in the calculator.
- Click Calculate to see the result and steps.
- Change one input and compare how the answer changes.
When to use it
Common mistakes
Enter only the elements or pairs requested. Avoid extra words unless they are part of the element names.
Discrete math often depends on empty sets, repeated items, self-pairs, and direction. Check these carefully.
A calculator can check examples, but proofs require explaining why the rule works for all valid cases.
Related calculators
FAQ
Formula Explorer connections
Interpretation: This relationship counts discrete structures, analyzes logic and sets, or describes algorithmic growth. Assumption: Define the sample space, recurrence, logical variables and counting constraints precisely. Avoid double counting and distinguish worst, average and best cases.