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.




[3..999,3].reduce('+,0) + [5..999,5].reduce('+,0) - [15..999,15].reduce('+,0)
233168