From New Scientist #674, 6th November 1969 [link]
Aunt Agatha has a lovely and unusual necklace made of uniform rings linked to form a continuous chain. Or at least, she had. But when she took it out of her drawer recently, she found that some links had been lost. She was left with seven separate pieces. One consisted of 11 links, one of 10, one of 9, one of 8, one of 7, one of 6, and one of 5.
“Never mind”, she said philosophically, “I’m sure it can be repaired. Tell you what, I’ll have it made up as two continuous necklaces of 28 links, as a gift for the twins”.
Mr Diamond the jeweller was consulted and agreed to undertake the work. He proposed to charge one shilling every time he opened a link and two shillings every time he closed one. Aunt Agatha accepted these terms and set about minimizing the bill.
How little need she have paid?
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