Find the fake coin in minimum weighings
You have 8 coins that look identical. One is fake and slightly lighter. Using a balance scale, find the fake coin!
You have 12 coins. One is fake (could be heavier OR lighter — you don't know which). Using a balance scale, find the fake in 3 weighings!
You have 3 coins. One is heavier (fake). Using a balance scale, find the fake in ONE weighing!
You have 9 coins. One is fake (you know it's heavier). Find the fake using the balance scale!
You have 5 bags of coins. Four bags have real coins (10g each). One bag has fake coins (9g each). You have one digital scale. How do you find the fake bag in ONE weighing?