Math Problem

[Renew Deal]

Very tricky math! Note: This must be done in your head only. Do NOT use paper and pencil or a calculator. Try it.








Take 1000 and add 40 to it. Now add another 1000. Now add 30. Add another 1000. Now add 20. Now add another 1000. Now add 10. What is the total?






Scroll down for answer..
























Did you get 5000? The correct answer is actually 4100.






Don't believe it? Check with your calculator! Today is definitely not your day. Maybe you will get the last question right?

[Sperk]

1. Almost fell for it., but I got it right....good thing, I'm a math tutor!

:evilgrin:

[ProfessorGAC]

2. How Would Anyone Get 5000?

I must be missing how someone would get fooled by that.

What would cause someone to add it up so they get 5000? There are 4 1,000's, and then the 40 through 10, by tens.

What am i missing?
The Professor

[aden_nak]

3. It's the way the problem is set up.

You are conditioned to only add digits in two columns, the tens column and the thousands column. So when the tens column carries over, many people will put the extra digit in the thousands column.

[ProfessorGAC]

5. OK?!?!?

I still don't get it. It seems to me that people would categorize in sequential order, so they'd 1000, 1040, 2040, 2070, 3070, 3090, 4090, and 4100. That's not how i did it, but that would be the normal sequence.

People tend to think in straight lines, so i still don't really get how people would get this wrong, even in their heads.
The Professor

[mrboba1]

8. by forgetting

that there is the hundreds column.
When you are adding 2 things like that, some people will skip the hundreds column because there was no mention of it before - only 1000's and 10's. So you add up the 3090 plus 1000 to 4090 and add another 10.
It doesn't work looking at it in print - it becomes obvious, but the mind could blur the 4 and the 9 to be next to each other and therefore you would combine and carry the extra '1' that is supposed to go in the 100's into the 1000's.

[aden_nak]

11. Exactly.

It's a simple device, really. You divert all of the attention to the specified locations, and you can get people to ignore what they should be paying attention to.

Works pretty well in politics as well.

[TXlib]

13. It almost got me.

[trotsky]

4. Depends on training, I think.

I had the same question - how would you get 5000?

But I approached it the same way you did - 4 x 1000 = 4000, and then add 40+30+20+10 (which is two groups of 50, which is 100). 4100.

I think the catch is that if in your mind you are adding them in order, you get to 4090, the brain might just tick over that 9 when you add 10 and think that the 4 needs to flip to a 5.

[ProfessorGAC]

6. Maybe So

For instance, on the 10 through 40 thing, i didn't even add those. I recognized that sequence as adding to a 100, so i didn't even do the math on that part. So, i said, "4 one thousands and that other 100 is 4100."

My training may have had me looking at similar values and multiplying, and then just recognizing the other sequence. If someone wasn't a math geek, they wouldn't have done it that way.

But, i still don't get it.

The Professor

[mrboba1]

10. But this problem is set up

in person and is not as effective in print. If someone asks you this (what is 1000 and 90 - you answer, then they ask the next part) you cannot look at similar values because there are none.

[chiburb]

14. Ok, I'll 'fess up....

I got 5000. And no, I can't explain it to you. You just have to be me...

[Donkeyboy75]

15. I'm with you, prof.

I added the thousands separately. But it seems that many people get caught, so it must "work" on some people.

[comradebillyboy]

7. you are right

there is an unconcious tendancy to add an extra zero to the multiples of 10. we think 140 instead of 1040. we drop the middle zero when we do it in our heads.

[DrWeird]

9. I don't get it.

Did anybody get 5000?

[rock]

12. (Sheepishly) yeah

[Donkeyboy75]

16. Nope. I pointed copper tubing at the problem first

to rid it of all chemtrails. That's how I got the correct answer.

[ScreamingMeemie]

17. Sure I almost did...and then I caught myself.

;)