Brain Teasers
3608528850368400786036725
What is so unusual about this number?
3608528850368400786036725
3608528850368400786036725
Hint
It's the greatest natural number with this property. If you can't figure it out, check out teaser 29716.Answer
The number formed by its first n digits is divisible by n, e.g. 36 is divisible by 2, 360 is divisible by 3, 3608 is divisible by 4, etc.Hide Hint Show Hint Hide Answer Show Answer
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Comments
Great teaser! Hard, though.
This ones too gud.......... difficult though
I love it!
I love it!
now thats a freaky number
i didnt know a number like this could exist
except a one-digit number maybe
i didnt know a number like this could exist
except a one-digit number maybe
Grrr........
Fascinating!!!
Fascinating!!!
Since it doesn't specify,a nd my curiosity has gotten the best of me, is that the SMALLEST? and is there any simple way to figure that out or just lots and LOTS of trial and error?
well, jsut thinking about it now, very quickly, 102000 is the smallest for 6
(2 into 10,
3 into 102,
4 into 1020,
5 into 10200,
6 into 102000 using the simple rules of even, add to multiple of 3, last 2 divisible by 4, 5 or 0, add to 3 and even).
Then it seems to get more complicated,
1020005/7 = 145715.
10200056, last 3 divisble by 8.
102000564 (digits add to multiple of 9 [18, singly])
1020005640 (ends in 0), so that is, i think, quite easily certifiable as the smallest up to 10.
10200056405/11 = 927277855 (any quick rule, for 11, or 7 for that matter, anyone?)
I guess this is where a dead end can be hit because not every set of ten numbers is sure to have a multiple of the next number (we could have hit that problem with 11, i believe, i dont know for sure). is there any way to realize which numbers keep going, or any better formula? very interested to hear it.
(Sorry for delayed reponses in a post, but I am currently doing the math out... 10200056405[x] (with x being between 0 and 9, aka the ones digit [not multiplied by, but as the last digit of that number]) yields only decimal answers [from 850047004 and 2/12 to 11/12] therefore stopping the trend at 11
(2 into 10,
3 into 102,
4 into 1020,
5 into 10200,
6 into 102000 using the simple rules of even, add to multiple of 3, last 2 divisible by 4, 5 or 0, add to 3 and even).
Then it seems to get more complicated,
1020005/7 = 145715.
10200056, last 3 divisble by 8.
102000564 (digits add to multiple of 9 [18, singly])
1020005640 (ends in 0), so that is, i think, quite easily certifiable as the smallest up to 10.
10200056405/11 = 927277855 (any quick rule, for 11, or 7 for that matter, anyone?)
I guess this is where a dead end can be hit because not every set of ten numbers is sure to have a multiple of the next number (we could have hit that problem with 11, i believe, i dont know for sure). is there any way to realize which numbers keep going, or any better formula? very interested to hear it.
(Sorry for delayed reponses in a post, but I am currently doing the math out... 10200056405[x] (with x being between 0 and 9, aka the ones digit [not multiplied by, but as the last digit of that number]) yields only decimal answers [from 850047004 and 2/12 to 11/12] therefore stopping the trend at 11
That is wicked sweet.
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