sum_square_difference.rb

# Problem #6 from http://projecteuler.net/problems

num = 10

def sum_of_squares(num)
  sum_of_squares = 0
  num.downto(1) do |number|
    sum_of_squares += number * number
  end
  sum_of_squares
end

def square_of_sums(num)
  sum = 0
  num.downto(1) do |number|
    sum += number
  end
  square_of_sums = sum * sum
  square_of_sums
end

def difference(num)
  difference = square_of_sums(num) - sum_of_squares(num)
  puts difference
end

sum_of_squares(num)
square_of_sums(num)
difference(100000000)