Today Puzzle #719
Puzzle No. 718 鈥� Thursday 16 April 2020
We're clapping again for the NHS at 8pm tonight. The NHS employs about 2 million people which makes it the world's fifth-largest employer. Suppose I do one clap, my neighbour does two, and the next house does four, then eight, sixteen and so on, doubling each time. How many households have to clap until there is one clap for every NHS employee?
Today’s #PuzzleForToday has been set by Dr Hugh Hunt, Reader in Engineering Dynamics and Vibration at Trinity College, Cambridge
Click here for the answer
21
For N people, total sum of claps is S = 1+2+4+8+...+2^(N-1) = 2 million
There is a formula for this: S = 2^N-1 from which N is about 21
The last household does one million claps!
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