Created
December 13, 2011 03:08
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Find the difference between the sum of the squares and the square of the sum
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#The sum of the squares of the first ten natural numbers is, | |
#12 + 22 + ... + 102 = 385 | |
#The square of the sum of the first ten natural numbers is, | |
#(1 + 2 + ... + 10)2 = 552 = 3025 | |
#Hence the difference between the sum of the squares of the first ten natural numbers and the square of the sum is 3025 385 = 2640. | |
#Find the difference between the sum of the squares of the first one hundred natural numbers and the square of the sum | |
ruby-1.9.2-p180 :004 > (1..10).to_a.reduce(:+)**2 - (1..10).to_a.map { |x| x**2 }.reduce(:+) | |
=> 2640 | |
ruby-1.9.2-p180 :005 > (1..100).to_a.reduce(:+)**2 - (1..100).to_a.map { |x| x**2 }.reduce(:+) | |
=> 25164150 |
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