A collection of logical problems and mathematical quizzes I found interesting.
There are 12 coins, ABCDEFGHIJKL, all visually identical but one is false, identifiable by difference in weight.
With only a balance, but no standard weights. in just three balances find the false coin and identify if it is heavy
The "False coin" problem was given to me as a challenge whilst walking along ridge in Umbria Italy by a fellow rambler. Took me a whole day to resolve.
The "3"s problem also set on the same ridge walk by another fellow rambler who in this case was a retired teacher and use to give this problem to his pupils.
Write the numbers 0 to 20 using three 3's and mathematical operators eg 5 = 3!-(3/3)