10 pigeons in 9 holes means that at least one hole is shared.
More from Chalkdust
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- Win a £100 Maths Gear goody bag by solving our infamous puzzle
- E Adrian Henle, Nick Gantzler, François-Xavier Coudert & Cory Simon team up for a deadly challenge
- Weddings, holidays and catfish find their way into the prof's postbox this issue.
- Goran Newsum always should be someone you really love