# mod not explained

• Mar 31st 2008, 11:49 PM
idontdomath
mod not explained
what is 3 to the power -1 (mod 29)?
• Apr 1st 2008, 02:01 AM
CaptainBlack
Quote:

Originally Posted by idontdomath
what is 3 to the power -1 (mod 29)?

You can think of modular arithmetic as clock arithmetic, so a number $\displaystyle {\rm{modulo}}~ 29$ is the remainder when that number is divided by 29.

In this case we are looking for a number $\displaystyle N$ in $\displaystyle [0,28]$ such that:

$\displaystyle 3N=29 \times k +1$

for some integer $\displaystyle k$

RonL
• Apr 1st 2008, 02:12 AM
angel.white
Quote:

Originally Posted by CaptainBlack
You can think of modular arithmetic as clock arithmetic, so a number $\displaystyle {\rm{modulo}}~ 29$ is the remainder when that number is divided by 29.

In this case we are looking for a number $\displaystyle N$ in $\displaystyle [0,28]$ such that:

$\displaystyle 3N=29 \times k +1$

for some integer $\displaystyle k$

RonL

That makes a lot more sense than what I was thinking (glad I kept my mouth shut ^_^)