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- 11 | abba, where a and b are the digits in a 4 digit number.
Truly lost here, I know abba could look anything like 1221 or even 9999 However how do I prove 11 divides all of the possiblities?
- How many $4$-digit palindromes are divisible by $3$?
Hint: in digits the number is $abba$ with $2 (a+b)$ divisible by $3$
- elementary number theory - Common factors for all palindromes . . .
For example a palindrome of length $4$ is always divisible by $11$ because palindromes of length $4$ are in the form of: $$\\overline{abba}$$ so it is equal to $$1001a+110b$$ and $1001$ and $110$ are
- How to calculate total combinations for AABB and ABBB sets?
Although both belong to a much broad combination of N=2 and n=4 (AAAA, ABBA, BBBB ), where order matters and repetition is allowed, both can be rearranged in different ways: First one: AABB, BBAA,
- sequences and series - The Perfect Sharing Algorithm (ABBABAAB . . .
The algorithm is normally created by taking AB, then inverting each 2-state 'digit' and sticking it on the end (ABBA) You then take this entire sequence and repeat the process (ABBABAAB)
- Matrices - Conditions for $AB+BA=0$ - Mathematics Stack Exchange
You'll need to complete a few actions and gain 15 reputation points before being able to upvote Upvoting indicates when questions and answers are useful What's reputation and how do I get it? Instead, you can save this post to reference later
- matrices - When will $AB=BA$? - Mathematics Stack Exchange
Given two square matrices $A,B$ with same dimension, what conditions will lead to this result? Or what result will this condition lead to? I thought this is a quite
- $A^2=AB+BA$. Prove that $\\det(AB-BA)=0$ - Mathematics Stack Exchange
I get the trick Use the fact that matrices "commute under determinants" +1
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