There are 9 coins, one of them is fake and weighs less. You can

First pick 3 and compare them to any other 3. Then you have it narrowed down to 3.

Then pick any one of the three and compare it to any other one

Put 4 one, 5 in the other.
Then do the same for the ones in the scale which weighed the least.
You could probably find it then.

>>8926098
>you could probably find it then

>>8926095
What about the third coin?

3 in one, 3 in the other.
Leave the rest out for now.
If it's shown that any of them weigh less, it'll be the right or left scales then, if not, then it's in the pile that didn't go on the scales.

Once you've done that, use your remaining chance to use the scales on those 3 coins, or compare them using something else.

>>8926116
Wait, no.
After that, there's 3 coins left.
Do the exact same procedure.
One in the left, one on the right scale.
If the scale tips, you've found your answer.
If they're balanced, then it's the remaining coin which is fake.

>>8926120
>>8926116
Well done fag

>>8926125
So here's a nearly-identical version:
12 coins, and you don't know whether it's heavier or lighter. You have three weighings to find out which and whether it's heavier or lighter.

>>8926088
>Weight 3 and 3, left 3 away
>You know which set of 3 coins have the fake one
>Weight one and one, left one away

>>8926112
You'll know it's that one if the two you put on the scale weigh the same

>>8926088
4 coins left & 4 coins right

If the coins weigh the same, you know the 9th coin is fake.

>>8926447
Kek

1) Weigh 3 vs 3. The lighter side has has your coin.

2) Take 1 coin from that pile of 3 and set it aside. Compare the remaining two on the scale. If both coins on the scale are equal, the coin is the one you set aside. If the scale shows an inequality, then that lighter coin is your coin.

EZ PZ

>>8926088
Put the fake one opposite a real one to check which falls lower. Do it once more with a different real coin just to be sure.

Are the coins made of steel or feathers?

>>8928095
They're made of one kilogramme