This has been posted in another section as well, just trying to find what I am looking for.
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About a year ago I found a site that had an addition problem that when added up in the way it was printed caused most people to get the wrong answer.

The problem was roughly something like:

Add these numbers from left to right in your head, not in a column on paper- 10 100 1000 10000.

Now, that is not the problem. But it is something like that. I took it to school and shared it with my students, most of whom calculated incorrectly. I have lost the problem, and the web link to the problem.

Thanks for any help with this.

I know exactly the problem you are looking for. The numbers run like; 1010,1100,1001 I believe. I have looked on the net with no avail. I may have it at home somewhere. If I can find it I'll post.

I seem to remember a different set of numbers, but Stan posted one on the other thread that works nicely.

My buddy Stan found it. It works most of the time. Try it. The link to the numbers is here.