A Personal Blog On Mathematical Sciences and Technology
Let have a Test:
You need to make a calculation. Please do neither use a calculator nor a paper. Calculate everything “in your brain”.
Take 1000
and add 40.
Now, add another 1000.
Now add 30.
Now, add 1000 again.
Add 20.
And add 1000 again.
And an additional 10.
So, You Got The RESULT! Be Quick! And Click here to check your result.
Quicker you see your result, sharper you are!
Do you think the result is 5000?
Actually, it is not. The correct result is 4100.
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it’s nice….
You got me. i was so proud when i came up with 5000 in a flash.
So now I know i’m not a genius…
Ha ha! When counting by head, one can make these kind of mistakes. Ask any math frequent buddy, you’ll probably get the same answer. Key point of this test is the last step: Four thousands and Ninety plus Ten equals what? : Five Thousand
I also first got with 5000 in an instant but when I understood my mistake, I figured out it as a awesome question.
I got 4100 after reading it, but if I had heard it, I would’ve probably gotten 5000.
Why: I saw four 1000′s and a group of four other numbers that I knew added up to 100, so I thought 4*1000 + 100. If I had heard it, the numbers would have been added in order (incorrectly) and I wouldn’t have been able to do this weird visual thing I do with numbers.
I got 3100….
You said take a thousand so I instantly thought to subtract a 1000 from zero to start off with making it -1000
Plus 40 makes it -960
Plus 1000 makes it 1040.
Add 30 makes it 1070
Add 1000 makes it 2070
Add 20 makes it 2090
Add 1000 makes it 3090
Add 10 makes it 3100.
-960 and plus 1000 makes only 40. so your answer should have been 2100.
As always, You’ve a great sense of humor!
witty
Fool me once shame on you, fool me twice shame om me.
I have had this puzzle before, so this time I got theright answer.
got it right the first time After the 30, i was expecting 20..and 10. As that sum is 100 + 4(1000); did not find it so tough
The calculation can’t possibly start by taking away a thousand, because two lines later, it states “add ANOTHER 1,000.” In order to add “another” 1000, there had to have been a first 1000. We know the first 1,000 is a positive number for two reasons: 1) There’s no minus sign in front of it, nor any mention of a negative, and 2) “Take” is an instruction to receive something, so we know we have received 1,000 with which to start the calculation. “Take away” would be the instruction to subtract.
I got the right answer, but did the math visually. I couldn’t help it, when I looked at the whole, the numbers added themselves. If that doesn’t happen, I easily get mired in the muck of mathematical “logic.”