Here's the puzzle of the month from the April 1960 issue of Popular Science [UPDATE: Readers with a better memory than mine have pointed out that I posted this romper la cabeza in 2005.]
Luckily someone told me the answer to this one at the same time as the puzzle. Otherwise –– like the wife of one PS editor –– I might still be working on it:
The census taker, placing one weary foot after another, climbed the steps and rang the bell. “How many people live here?” he asked the person who answered the door.
“Three,” was a prompt answer.
“And their ages?”
The reply startled him: “the product of our ages is 225, while the sum is the same as the house number.”
The census taker looked up to check the number he had already noted on his tally sheet, “Hmm,” he said, “I need to know one more thing: are you the eldest?”
“Why, yes,” the person said. And the census taker, cheered at the novel answers, smiled as he wrote down their ages and walked away.