Task

The objective is to write a function that finds the sum of all positive multiples of 3 or 5 below n.

Show output for n = 1000.

This is is the same as Project Euler problem 1.

Extra credit: do this efficiently for n = 1e20 or higher.




def sum_3_5_multiples(n)
  (0...n).select { |i| i % 3 == 0 || i % 5 == 0 }.sum
end
 
puts sum_3_5_multiples(1000)