So I'm watching Andrew Marr's History of the World (thank you iPlayer) and up to part four.
Among tonight's astonishing moments comes learning about Al-Khorezmiy who in 827CE calculated the circumference of the Earth damned near accurately. Marr tells me that the ancient Islamic genius calculated the circumference as 23,200 miles and that it's "remarkably close to the accurate calculation" but (infuriatingly) doesn't tell me what that accurate calculation is.
I naturally hit pause and ask Siri (he says 24,901.42 miles incidentally) my sense of C21st curiosity sated I resume the program. Only to learn that Al-Khorezmiy is also in a sense, the father of the algorithm, and since that sort of mathematical acrobatics is essential to modern computing (as Marr mischievously puts it) "every time you pick up your mobile phone, remember there's an old Uzbek Muslim hidden inside".