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.




// simple version:
sum35 = function(n)
    sum = 0
    for i in range(3, n-1, 3)
        sum = sum + i
    end for
    for i in range(5, n-1, 5)
        if i % 3 then sum = sum + i // (skip multiples of 3 here)
    end for
    return sum
end function
 
print sum35(1000)