When Harry bought his train ticket, he received £$$2.50$$ in change. He noticed that for each coin in his change, there was~\uline{exactly}~one other coin of the same value. What was the coin of smallest value in Harry\textquotesingle s change?  Answer~\uline{~~~~~~~~~~}~ 
Overseas Competition->Knowledge Point->Combinatorics->Logical Reasoning->Reasoning by Conditions->Complex Reasoning 