# FAQ: Introduction to JavaScript - Arithmetic Operators

This community-built FAQ covers the “Arithmetic Operators” exercise from the lesson "Introduction to JavaScript ".

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3 posts were split to a new topic: What is the difference between printing `3 + 4` and `'3 + 4'`?

Kind of a funny lesson =)

2 Likes

7 posts were split to a new topic: How does Javascript handle a negative modulo? (`-5 % 20`)

why is it when i do ‘‘console.log(240/65)’’. it says ‘‘Did you divide 65?’’

2 Likes

Are you sure of your understanding of `divide 65 by 240`?

2 Likes

yeah i do understand

So have you sorted out your question, then?

Do I need to put spaces between the symbols in parentheses or it’s ok to go without them? like “console.log(3 + 4)” or “console.log(3+4)”

1 Like

Welcome, @py9568079721.

No, spaces are not needed; however, keeping white space around operators lets them stand out and makes readability and debugging much easier so it is recommended.

``````y = m * x + b
``````

as opposed to,

``````y=m*x+b
``````
3 Likes

Idk why im even paying for this site…

var age = 21;
console.log(age + 3.5);

Results in the Console logging 24.5

Still i the Result doesnt count and i need to go to baby level ???
console.log(21 + 3.5);

Did the instructions ask us to create a variable for our age? Seems the author meant for us to literally write it into the console.log() statement.

P. S. Griping is not going to win you much support. Pull up your socks and invest yourself. Forget about the money. The real investment is your attitude and effort.

“/” is the JavaScript way to divide

Why does the remainder of console.log(5%20) = 5 and not 0?

Might want to recheck your math, there. 5 % 21 is 5. 21 % 5 is 1.

Can you use the remainder operator when using decimal numbers?

Yes, we can, though we need to be able to interpret the outcomes. Bear in mind that floating point math is not the same as integer math so we likely won’t see `0` as the result even if a number is divisible.

Eg.

``````console.log(2.25 % 0.15)    //  8.326672684688674e-17
``````

Compare this to,

``````console.log(225 % 15)    //  0
``````

The simplest use case is where the divisor is unity (1).

``````console.log(3.14 % 1)    //  0.14000000000000012
``````

Note again the floating point arithmetic error. We have very nearly extracted the decimal portion of the dividend though we have to mitigate the error to arrive at the actual value, `0.14`.

As a predicate to determine if a value is float or not,

``````if (n % 1 === 0) {
// n is an integer or very nearly one; 3.0 => 3
} else {
// n is a float
}``````
1 Like

Thank you! So in a simple sense, a float number doesn’t compute properly through the remainder operator?

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In as much as we have to contend with the arithmetic error, no; it is much better suited to integer division.

1 Like

@ mtf good note on spaces between the input. did not think about debugging

1 Like