How to calculate a Modulo? I really can't get my head around this "modulo" thing. 
Can someone show me a general step-by-step procedure on how I would be able to find out the 5 modulo 10, or 10 modulo 5. 
Also, what does this mean: 1/17 = 113 modulo 120 ? 
Because when I calculate(using a calculator) 113 modulo 120, the result is 113. But what is the 1/17 standing for then? 
THANK YOU! 

When you see "modulo", especially if you are using a calculator, think of it as the remainder term when you do division.
Examples:
The result of 10 modulo 5 is 0 because the remainder of 10 / 5 is 0.
The result of 7 modulo 5 is 2 because the remainder of 7 / 5 is 2.
The reason your calculator says 113 modulo 120 = 113 is because 113 < 120, so it isn't doing any division.
More generally, the idea is that two numbers are congruent if they are the same modulo a given number (or modulus)
For example, as above, $7 \equiv 2 \mod 5$ where $5$ is our modulus.
Another issue is that of inverses, which is where the confusion of $1/17$ comes in.
We say that $a$ and $b$ are inverses modulo $n$, if $ab \equiv 1 \mod n$, and we might write $b = a^{-1}$.
For example $17\cdot 113 = 1921 = 120\cdot 16 +1 \equiv 1 \mod 120$, 
so $17^{-1} = 113$ modulo $120$.
