⟩ In 80 coins 1 coin is counterfeit which is minimum no. of weighings to find out counterfeit coin?
split the coin into 26 26 26......
take any 2 26 coins.....
if it is = the odd coin isin remaining 26,
if any one has less or more wt, go for nxt and find it..
so it takes 2 trials.....
9,9,9
3,3,3
1,1,1.....
5 trials or 6 trials