Brain Teasers
Largest Number
What's the largest natural number that satisfies this condition:
Each digit from the third on equals the sum of its two preceding digits.
Each digit from the third on equals the sum of its two preceding digits.
Answer
To make a largest number, we need the most number of digits. So we should start with the smallest digits possible. The first digit is at least 1, and the second digit can be 0.So, the largest number we are looking for is 10112358.
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Comments
The wording confused me. I got 819 because I thought it had to be a 3-digit #. Good one though.
If "it had to be a 3-digit"... why not 909?
ok....sure.
LOVED IT, but didn't get it right, keep them coming
0 doesn't equal 1+1
Dec 21, 2005
Actually this is a Fibonacci Sequence and the largest number has yet to be found.
Nice puzzle. I especially like the logical explanation. I should have been more patient and maybe I would have solved it!
Dec 23, 2005
Not to be picky, but shouldn't the first digit refer to the "ones" digit?
good teaser. keep them coming
twymer, this is a Fibonacci Sequence, but the next number in the sequence is 13 which isn't a single digit, so it doesn't match the criteria for this teaser.
Good one.
Unfortunately I and many others does not know what is meant by a 'natural number' so was not able to try for a solution.
When compiling questions can I ask the submitter to carefully explain anything that may be not known by all - especially non english speakers.
Suggest you try the question out on your friends first and see if they understand it clearly.
Thanks again
Unfortunately I and many others does not know what is meant by a 'natural number' so was not able to try for a solution.
When compiling questions can I ask the submitter to carefully explain anything that may be not known by all - especially non english speakers.
Suggest you try the question out on your friends first and see if they understand it clearly.
Thanks again
Thank you. You can feel free to correct it, in order to clarify it.
Got the answer right. The idea is to have as many digits as possible so one must start with 1 and 0 and from there create the number desired.
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