7-Day Venn Diagram Streak
Draw one Venn diagram a day comparing two everyday groups, like fruits and red things. Check in daily.
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Science · Facts & stats · iChallenge network
Daily facts and stats about sets in mathematics, plus real challenges to put them to work.
What is a set with no elements called?
The empty set, written ∅ or {}, contains nothing at all.

One ranked attempt per day. Practice as much as you like.
Join one, log your days or post your proof. Finishing earns XP and the Finisher badge.
Draw one Venn diagram a day comparing two everyday groups, like fruits and red things. Check in daily.
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Sort a real collection, like buttons or books, into sets and overlaps, then post a photo link or short write-up of your Venn diagram.
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Solve one logic or set puzzle each day for ten days. Check in daily.
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Everyone on this arena gets the same five questions each day, from easy to hard. You get one ranked attempt; practice rounds are unlimited.
100 points per correct answer, up to 50 more for answering quickly, a combo multiplier for answers in a row, and 150 bonus points for a perfect round.
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