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Let $a$ be an integer such that $a \equiv 5 \pmod{7}$. Find the value of $a + 1 \pmod{7}$. Express your answer as a residue between $0$ and the modulus.

 Aug 1, 2024
 #1
avatar+1926 
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mmm...not sure about my solution, but here it is. 

First, we have the modulo 

\(a \equiv 5 \pmod{7}\)

 

Since we must find a+1 mod 7, let's add 1 to both sides of our equation to get

\(a+1 \equiv 5+1 \pmod7\\ a+1 \equiv 6 \pmod7\)

 

We can test numbers. 

Let's test 5, 19, 26

 

\(6 \equiv 6\pmod7\\ 20 \equiv 6 \pmod 7\\ 27 \equiv 6 \pmod 7\)

 

So 6 is our answer. 

 

Thanks! :)

 Aug 1, 2024
edited by NotThatSmart  Aug 1, 2024

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