FAQ: Code Challenges: JavaScript Fundamentals - numImaginaryFriends()


This community-built FAQ covers the “numImaginaryFriends()” exercise from the lesson “Code Challenges: JavaScript Fundamentals”.

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This exercise can be found in the following Codecademy content:

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FAQs on the exercise numImaginaryFriends()

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Hello. Why does 33 percent need to be written as 0.33 and not 33% ?


0.33 is a literal which can be used directly in calculations. 33% is an abstract which would need to be parsed and interpreted before it can be evaluated. It would have to be written in string form else the JS interpreter will see it as a number followed by the modulo operator and missing an operand so would raise an error.

33 % 10 === 3

If we wish to output to the display, then,

pct = 0.33;
`${pct * 100}% of voters were undecided.`

Note that % is string character.


Why is

const numImaginaryFriends = totalFriends => Math.round(totalFriends * .33);

correct while

const numImaginaryFriends = totalFriends => { Math.round(totalFriends * .33); }

throws an error?


It’s the curly braces. When using a block like that, there is no implicit return. It must be explicit.

    return ...;


Ah, OK. Thanks for the quick reply @mtf.


Can someone explain to me why I can’t write (1/3) instead of .33?

const numImaginaryFriends = totalFriends => Math.round(totalFriends * (1/3))

I end up with an error saying:

Your function should return a whole number ie 1.3 should round down to 1 while 4.9 should round up to 5

 > totalFriends = 8
=> 8
> Math.round(totalFriends * (1/3))
=> 3
 > totalFriends = 7
=> 7
> Math.round(totalFriends * (1/3))
=> 2

It’s not a problem for JS, but may be a problem with the answer the SCT is seeing. Check the instructions and be sure to follow them to the letter.