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Muhammad ibn Musa al-Khwarizmi: 2 puzzles worth knowing

2 puzzles from Muhammad ibn Musa al-Khwarizmi, each explained in a minute and credited to the original work. Free on Savvy.

• Split 10 into two parts where one part squared is four times their product

  Divide the number ten into two parts. Multiply the two parts together, and separately multiply one of the parts by itself. It turns out the self-multiplied result is exactly four t…

  — Muhammad ibn Musa al-Khwarizmi, The Compendious Book on Calculation by Completion and Balancing

• The Widow's Estate and the Stranger's Share

  A woman dies leaving a husband, a son, and three daughters, and a will that bequeaths a stranger exactly 1/8 plus 1/7 of her whole estate. By the inheritance law of the time, the h…

  — Muhammad ibn Musa al-Khwarizmi, Al-Jabr (The Compendious Book on Calculation by Completion and Balancing)

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