Comments on: Yoak: Simple Arithmetic

By: Stephen Morris

Stephen Morris — Thu, 22 Oct 2009 00:04:13 +0000

There is a very long running and popular game show in Britain which has exactly this kind of problem. You can try it out for yourself here. http://www.dilan4.com/maths/countdown.htm If you search for 'countdown number game' you will find many sites which solve them for you. I couldn't find any which solve this particular problem, they all make an assumption which isn't valid here.

By: jyoak

jyoak — Sat, 10 Oct 2009 17:17:10 +0000

Here's the answer:

[spoiler] 6/(1-(3/4)) [/spoiler]

By: jyoak

jyoak — Wed, 07 Oct 2009 17:50:56 +0000

Andy, I'm happy to have you call it fairly difficult. I was worried that this was trivial to anyone except me. :-) Calling it a trick might be a stretch, but Blaine's comment would have caused me to realize it instantly as well.

By: jyoak

jyoak — Wed, 07 Oct 2009 17:49:42 +0000

Bud, yes, that's exactly what I had in mind. You use a total of three operators plus any number of parenthesis you like and they may either be all different, two the same and one different or all different. The numbers must be used exactly once each.

By: Bud

Bud — Wed, 07 Oct 2009 17:18:24 +0000

I assume that it’s OK to use the operators more than once, but each number can appear only once?

By: Andy

Andy — Tue, 06 Oct 2009 03:18:48 +0000

I found this to be fairly difficult. I didn’t get it until the hint from Blaine (although then I got it immediately).

By: Blaine

Blaine — Mon, 05 Oct 2009 21:37:41 +0000

There’s a trick to it and it isn’t immediately obvious.[spoiler]I won’t give it away but if you can correctly answer “What is 10 divided by 1/2?” you’ll know how to solve this.[/spoiler]