# Lesson 20, how to understand Modulo itself?

#1

OK, so I am doing lesson 20 of Javascript.

unfortunately I do not understand the Modulo.

[So if we do 23 % 10, we divide 23 by 10 which equals 2 with 3 left over. So 23 % 10 evaluates to 3.

More examples:

17 % 5 evaluates to 2

13 % 7 evaluates to 6]

Where does the answer 3, 2 and 6 come from? How to calculate it?

#2

+++++++++++++++++ for loop wrong FIZZ BUZZ condition in DIAGRAM
Javascript has the so-called Remainder-operator %
is actually a modulo-operator
and if used it will return the rest-value.

9%3 You read it as nine modulo three is zero, as 9 divided by 3 has NO rest-value.
22%6 You read 22 modulo six is 4, as 22 divided by 6 will leave you with rest-value 4
10%5 You read 10 nodulo five is zero, as 10 divided by 5 will have NO rest-value

In this section you have to figure out
(i%3 === 0 && i%5 === 0) to display FizzBuzz // if (imodulo 3 equals zero AND imodulo 5 equals zero)
(i%3 === 0) to display Fizz // else if (i modulo 3 equals zero )
(i%5 === 0) to display Buzz // else if (i modulo 5 equals zero )
AND
if none of the above display i //else display i

You will have to use an IF ELSE-IF ELSE-IF ELSE-statement
within a for-loop.

``````program
flow
|
V                                                - - - -
for(var i=1;i<21;i++){ - - - - - i >= 21 - - - - - -> | EXIT |
|            |                                           - - - -
^            V
|         (i < 21)
^            V
|           if (i%3===0 && i%5 ===0 ){
|                console.log("FizzBuzz"); - - - > - - - -+
|           }                                            |
^           else if (i%5===0){                           V
|                console.log("Buzz"); - - - ->- - - - - -+
|           }                                            |
^           else if (i%3===0 ) {                         V
|                console.log("Fizz"); - - - -> - - - - - +
|           }                                            |
|           else {                                       V
|                console.log(i); - - - - - - - - -> - - -+
|           }                                            |
^ - - - - - -< - - - - - - < - - - < - - - - - < - - - - +
}``````

== the Book ==
javascript remainder operator site:developer.mozilla.org
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Arithmetic_Operators
the for-loop:
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for

== discussions / opinions ==
javascript remainder operator site:stackoverflow.com
http://stackoverflow.com/questions/4467539/javascript-modulo-not-behaving
javascript array site:developer.mozilla.org
https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array

== guidance ==
www.crockford.com
http://javascript.crockford.com/survey.html
http://javascript.crockford.com/code.html `<<< Javascript coding conventions`

#3

Hi! I have the same doubt as you, I've red the answers from @leonhard.wettengmx.n and still don't understand it. Could you explain it to me? Thanks