A 3,600-year-old Egyptian scroll hides the same trick as a children's rhyme about St Ives
Problem 79 of the Rhind Mathematical Papyrus, copied around 1650 BC, describes a chain of sevens: 7 houses, each with 7 cats, each cat catching 7 mice, each mouse eating 7 grains of wheat, each grain capable of producing 7 hekat measures of grain. It's asking you to add up the whole chain of quantities at once.
Reveal the answer
The total comes to 19,607, arrived at using geometric-series arithmetic that predates algebra as we know it. The rhyme "As I was going to St Ives" (seven wives, seven sacks, seven cats, seven kits) uses the exact same nested structure, and the resemblance is close enough that historians of mathematics regularly cite the ancient Egyptian problem as either an ancestor of the riddle or a case of the same puzzle form being reinvented independently.
— Ahmes (scribe), Rhind Mathematical Papyrus — c. 1650 BCE, British Museum