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Birthday Party

Stage: 2 and 3 Short Challenge Level: Challenge Level:1
See all short problems arranged by curriculum topic in the short problems collection

You are told that 30 pupils have 25 different birthdays between them. What is the largest number of these pupils who could share the same birthday?
 
If you liked this problem, here is an NRICH task which challenges you to use similar mathematical ideas.
  

This problem is taken from the UKMT Mathematical Challenges.