Set theory is the foundation of modern mathematics. Calculate A∪B, A∩B, A−B and symmetric difference.
Union (A∪B) combines all elements. Intersection (A∩B) keeps only shared elements.
Reach for this calculator when you need a result you can act on confidently. The formula is straightforward, but manual computation introduces rounding errors that this tool eliminates entirely.
A common mistake is applying the formula in the wrong direction — particularly with percentage and ratio problems, where the part and the whole can be mistakenly swapped. Check which value is the reference (the 'whole') before entering inputs.
A shopper sees two versions of the same product at different prices: one at £14.50 for 400g and another at £11.99 for 300g. Running both price-per-gram calculations reveals the larger pack is 7% cheaper per unit — the kind of comparison that is impossible to do reliably in your head at the shelf.
Union combines all elements from both sets. Intersection keeps only elements that appear in both sets.
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