Proof+250 XP
100 Coin Flips
Flip a coin 100 times, record how many heads you get, and post your tally with a note on how close it came to 50.
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Science · Facts & stats · iChallenge network
The Risk Challenge
Daily facts and stats about risk and probability, plus real challenges to put them to work.
Warm-up questionNot ranked · tap an answer
What is 'expected value' in probability?
Expected value weights each outcome by its probability, giving the long-run average.
Level1Rookie
XPPlay a round to earn XP
Streak0days
LeagueBronzeweekly
Daily #3Resets at midnight UTC
Today's round
- 5 questions
- 20s each
- 0 played today
One ranked attempt per day. Practice as much as you like.
Challenges
Join one, log your days or post your proof. Finishing earns XP and the Finisher badge.
Streak · 7 days+185 XP
7-Day Home Safety Spot
Each day, spot and fix one small everyday hazard at home, like a loose cord or a cluttered step. Check in once a day.
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Proof+250 XP
Two-Dice Chart
Roll two dice 50 times, chart how often each total appears and post your chart.
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By the numbers
Live counts from RiskChallenge.com. All arena stats →
Facts in the pack12
Visitors, 30 days75
Leaderboard
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Badges
Earned on any arena, shown on your profile everywhere.
First RoundFinish your first daily round.
FlawlessAnswer every question in a round correctly.
LightningA perfect round in under 25 seconds.
On a RollPlay 3 days in a row.
Week WarriorPlay 7 days in a row.
UnbreakablePlay 30 days in a row.
ExplorerPlay daily rounds in 5 different arenas.
GlobetrotterPlay daily rounds in 25 different arenas.
PolymathPlay daily rounds in 5 different topics.
In the ArenaJoin your first challenge.
FinisherComplete a challenge.
RecruiterInvite a friend who finishes a round.
CaptainInvite 5 friends who finish a round.
PodiumFinish a day in an arena's top 3.
ChallengerReach level 10.
Profile SavedSave your progress with an email.
Save your progress
Add your email to keep your level, streak and badges if you switch devices, and carry them to every iChallenge arena. One email when you save; no spam.
Put a prize on a challenge
Fund a prize on RiskChallenge.com and your brand sits on the challenge card, the leaderboard and every finisher's share. Prizes only appear once they're funded, so players can trust what they see.
- Pick the challenge and the prize
- We review entries before a funded prize is awarded
- You get finisher and engagement numbers after it closes
Current sponsors
Questions
Is this financial advice?
No. These are educational games and habit challenges, not advice.
How do I win?
Play the daily round and finish challenges. Leaderboards rank XP for today, this week and all time.
How does the daily round work?
Everyone on this arena gets the same five questions each day, from easy to hard. You get one ranked attempt; practice rounds are unlimited.
How is my score calculated?
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.
Is it free?
Yes. Playing, streaks, badges and leaderboards are free. Some challenges carry a sponsor-funded prize; the challenge card shows it when one is funded.