Philosophy of Mathspeaking topic
Add up the reciprocals of the natural numbers (1 + 1/2 + 1/3 + ...) and the sum grows to infinity; add up only the reciprocals of the primes and it still grows to infinity. Primes keep thinning out, yet they are enough to overflow the sum. How can such 'rare' numbers be this powerful?
— the series of reciprocals of the primes
practice with this topic
Set the timer (5-30 min), take 20 seconds of prep if you like, start talking. Jot your thoughts onto the sticky-note board.
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