Difference between revisions of "G285 2021 MC-IME I"

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[[G285 2021 MC-IME I Problem 1|Solution]]
 
[[G285 2021 MC-IME I Problem 1|Solution]]
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==Problem 2==
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If the number <math>abcd_{11}</math> is a palindrome in base <math>7</math>, and <math>dcba</math> expressed in base <math>10</math> does not begin with a nonzero digit, find the  difference between the largest and smallest possible sum of <math>a+b+c+d</math>.
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[[G285 2021 MC-IME I Problem 2|Solution]]

Revision as of 17:57, 8 June 2021

Problem 1

Let a recursive sequence $a_n$ be defined such that $a_1=20$, and $a_n=16a_{n-1}+4$. Find the last $4$ digits of \[\sum_{i=1}^{100} a_i\]

Solution

Problem 2

If the number $abcd_{11}$ is a palindrome in base $7$, and $dcba$ expressed in base $10$ does not begin with a nonzero digit, find the difference between the largest and smallest possible sum of $a+b+c+d$.

Solution