Henry Ernest Dudeney/Puzzles and Curious Problems/352 - Locating the Coins

by : $352$

 * Locating the Coins
 * Said Dora to her brother:
 * "Put a shilling in one of your pockets and a penny in the pocket in the opposite side.
 * Now the shilling represents $12$ and the penny $1$.
 * Triple the coin in your right pocket, and double that in your left pocket.
 * Add these products together and tell me whether the result is odd or even."


 * He said the result was even, and she immediately told him that the shilling was in the right pocket and the penny in the left one.
 * Every time he tried it she told him correctly how the coins were located.
 * How did she do it?