From: Todd Benson <caduceass@...>
Date: 2008-10-19T05:30:08+09:00
Subject: Re: Counting

On Sat, Oct 18, 2008 at 10:02 AM, Craig Demyanovich
<cdemyanovich@gmail.com> wrote:
> The OP needs multiples of 2 and 6. Since all multiples of 6 are also
> multiples of 2, just checking for multiples of 6 suffices. However, if d =
> 6, your two approaches don't produce the same result. For d = 6, they
> produce 83498 and 83166, respectively. 83166 is the correct answer, I
> believe.

Well, I don't think he meant all multiples of (2 AND 6), or in this
case (2 AND 5).  That will always be simply always be multiples of the
LCM, which, for (2 AND 6) is 6, for (12 AND 18) is 36, for (2 AND 5),
10, etc.

lcm = 2.lcm 5
puts (1..1000/lcm).map.inject {|s, i| s + i * lcm}

I think he meant (multiples of 2) AND (multiples of 6), or in this
case (multiples of 2) AND (multiples of 5), which would be multiples
of either.  In that case check whether the number is cleanly divisible
by number a and number b using %.

Todd