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Three boys each with a 10 cents go to the ice cream parlor to buy a pint of ice cream (at 30 cents a pint). After departing from the store, the proprietor reminded the clerk that the sale price for the day was 25 cents a pint and that he should refund the boys a nickel. 

So the clerk grabbed five pennies, caught up with the boys and gave them each one penny and kept two for himself. Each boy receiving a penny change meant that the boys have now spent only nine cents and two cents remained with the clerk.

3 boys X 9 = 27 + the 2 cents the clerk kept = 29 cents ! What happened to the other penny?



The Triangle quandary

Below lies two identical triangles. Each is made up of four identical pieces (shapes).

How is it possible the one at the bottom has a square hole lessening the visible surface area by one unit?