assume yu hav a balans skale,
1. put 3 koins in 1 pan & 3 in other pan.
2. if pan balans, bad koin not in this bunch av 6 koins...tri the other 3
from other 3, put 1 koin in 1 pan & 1 in other pan.
If it balans, bad koin is the 1 koin yu did NOT put in a pan.
If it dont balans in step 1 or 2, 1 koin in 1 pan is bad, but yu dont no wich.
Take 3 koins from 1 pan & split it intu ...like step 2 & maeby 1 pan hevee or not
Problem...if yu dont no if bad koin is hevee or lite, yu kant be shuer after 3 steps
take xtra step the chek that.