Please Help Me Figure This Riddle Out!

[Seahunt]

I can't figure this out - why does this happen?
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Riddle -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!
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OK - I don't understand why this happens!

Why does the calculator add this incorrectly? Or am I having a "Duh" moment here? I've added and added, and see where my calculator screws it up, but why? Glitch in all calculators? Mine is pretty old....

 

[floridaminnie]

There's an extra 1000 that doesn't belong there.

 

[Michelle]

Umm, don't know about the calculator but I added it in my head and got the right answer.

 

[HeyMickey]

Yeah... worked for me too.

 

[#1 Disney Fan]

The calculator is not miscalculating, it is 4100. You sum up the numbers to 4090... then you add 10 and due to the way that you've been adding numbers your head tries to trick you into wanting to change the 4 to a 5 instead of adding a 1 in the hundreds column.... but of course 4090+10=4100, not 5000.

Hope that helps!

 

[floridaminnie]

I see now. Silly ol' me!

 

[Dan Murphy]

Engineer Lynne said what I was going to say, LOL.

 

[Seahunt]

Thanks for helping with this! I can see now where you're adding to the 5000 instead of 4100 - it's just like you said it's where you add the last 10 to the 4090 and your mind can trick you! Definitely a DUH moment for me!