1
$\begingroup$

Add ONLY ONE line (does not have to be a straight horizontal line or in other words, doesn't need to be an axis aligned to the equal sign) to make the equation below true :

EQUATION :

$5$ $+$ $5$ $+$ $5$ $=$ $555$

Notes And Clarification :

  • Crossing the equal sign is not allowed

  • Making a less or more than sign (≤ or ≥) is also not allowed

  • This is not a duplicate of $5$ $+$ $5$ $+$ $5$ $=$ $550$

  • The answer with the most votes will get the green checkmark

Improve this question
$\endgroup$
12
  • 1
    $\begingroup$ Are you sure you didn't mean "= 550"? $\endgroup$
    – Alconja
    Commented Oct 16, 2018 at 4:46
  • 1
    $\begingroup$ Nope, this is a new one :D @Alconja $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 4:52
  • 1
    $\begingroup$ Does the line need to be perfectly straight like it did in the 550 question? $\endgroup$
    – Arpeggio
    Commented Oct 16, 2018 at 5:36
  • 2
    $\begingroup$ @RyanTheLeach it doesn't need to be "an axis aligned to the equal sign" :D $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 7:47
  • 3
    $\begingroup$ @xhienne I meant that the highest answer (apart from GeorgeMenoutis's answer coz that's a clarification) will get the checkmark in the end :D $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 8:04

15 Answers 15

Reset to default
23
$\begingroup$

This equation is true

... in base 14:

$5 + 5 + 5 = 55 / 5$

(in base 14, 5 + 5 + 5 = 11)

Improve this answer
$\endgroup$
5
  • $\begingroup$ A really creative answer (+1) :D $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 8:43
  • $\begingroup$ this one is a nice answer really $\endgroup$
    – Shahriar Mahmud Sajid
    Commented Oct 16, 2018 at 8:46
  • 1
    $\begingroup$ Thanks guys, but I'm quite sure this is not the expected answer and I can't help feeling like I'm kind of cheating ;-) $\endgroup$
    – xhienne
    Commented Oct 16, 2018 at 8:57
  • 2
    $\begingroup$ puzzling is for fun! You can see some really weird solutions around... $\endgroup$
    – George Menoutis
    Commented Oct 16, 2018 at 11:09
  • 1
    $\begingroup$ @Vincent 55 in base 14 is equal to 75 in base 10 (ie. 5 x 14 + 5). However, 11 in base 14 is equal to 15 in base 10 (ie. 1 x 14 + 1). Hence in base 14, 55/5 = 11 is true, because it is equivalent to 75/5 = 15 in base 10. $\endgroup$
    – El-Guest
    Commented Oct 16, 2018 at 15:14
18
$\begingroup$

Using brute force of one heavy stroke line, answer could be :

enter image description here

Or using correction fluid :

enter image description here

Improve this answer
$\endgroup$
15
$\begingroup$

The one line to be added is:

If we define '+' as string concatenation, the following equation holds:

It needs to be added in front of the equation.

Improve this answer
$\endgroup$
3
  • 2
    $\begingroup$ In my opinion, whoever upvotes this answer should also upvote Naeem Shaikh's answer. $\endgroup$
    – xhienne
    Commented Oct 16, 2018 at 12:57
  • 4
    $\begingroup$ @xhienne: My answer is a play on the wording "one line", so I would say that it is a succinctly different solution. $\endgroup$
    – M.Herzkamp
    Commented Oct 16, 2018 at 13:03
  • $\begingroup$ Oh, you are right, sorry I missed the subtlety of your answer. $\endgroup$
    – xhienne
    Commented Oct 16, 2018 at 13:05
13
$\begingroup$

Add ONLY ONE line (does not have to be straight)

 

yee
(Line is curvy)

Improve this answer
$\endgroup$
2
  • 2
    $\begingroup$ Very clever but that would be too easy. Nevertheless, (+1) from me :D $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 14:05
  • $\begingroup$ This is the best answer xD $(+1)$ $\endgroup$
    – Mr Pie
    Commented Oct 17, 2018 at 2:42
12
$\begingroup$

Given 5+5+5=555 You can make the equation true by adding one line (or symbol).

The angle/ degree symbol.

Where:

5+5+5 = ∠555 (or 555°)

Given that:

the override of ∠555 is 195° (or 15°)).

Therefore:

5+5+5 = ∠555 (or 15° = 555°)

Image:

enter image description here

[Edit] Added further text to include comments that note how my answer can be written in two ways (where one of those two can be drawn with two lines depending on an individual's way of writing).

Improve this answer
$\endgroup$
5
  • $\begingroup$ Welcome to Puzzling SE! Love the cleverness of this answer and well formatted, keep up the good work! $\endgroup$
    – gabbo1092
    Commented Oct 16, 2018 at 15:53
  • $\begingroup$ You can argue that the angle line is actually two lines. $\endgroup$
    – Tejas Kale
    Commented Oct 16, 2018 at 16:08
  • 1
    $\begingroup$ You very well could - at that point, it becomes the digression of the viewer and how they personally write/ pen the angle line. Such as how you can write "2," "5," "7," or "8" with one or two pen lines for instance. :) $\endgroup$
    – AnonyTech
    Commented Oct 16, 2018 at 16:11
  • 5
    $\begingroup$ Clever one, you could also add one circular line telling : 5+5+5=555° $\endgroup$
    – user43301
    Commented Oct 16, 2018 at 16:15
  • $\begingroup$ this is the best answer so far $\endgroup$
    – Shahriar Mahmud Sajid
    Commented Oct 17, 2018 at 4:28
6
$\begingroup$

This is already true in javascript, if the value 5 is typecasted to string before the equation.
var a = '5'; var result = a + a + a; // produces 555

Improve this answer
$\endgroup$
2
  • 1
    $\begingroup$ Nice try but not the intended one :D $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 7:44
  • $\begingroup$ In this case, the line could be ` since that denotes code in Markdown. :) ... though I'm not sure that it works without the matching tick on the end! $\endgroup$
    – feelinferrety
    Commented Oct 16, 2018 at 16:30
5
$\begingroup$

My try!

Working modulo $5$, $$5+5+5\equiv555$$ Actually, this works modulo $k$ whenever $k\mid 540$.

Improve this answer
$\endgroup$
5
  • 2
    $\begingroup$ Yes, this can be the answer but I'm still waiting for others to come up with better ones (+1) :D $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 7:44
  • 2
    $\begingroup$ Please tell me you have an answer in mind? $\endgroup$
    – Ryan Leach
    Commented Oct 16, 2018 at 7:46
  • 1
    $\begingroup$ @RyanTheLeach Oh I do myself but I'm sure others have even more $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 7:46
  • 2
    $\begingroup$ @TheSimpliFire I don't understand your solution. The symbol you used means 'equivalence' or 'identical to'. How does that work? $\endgroup$
    – rhsquared
    Commented Oct 16, 2018 at 7:52
  • 4
    $\begingroup$ @rhsquared Congruences $\endgroup$
    – TheSimpliFire
    Commented Oct 16, 2018 at 7:54
5
$\begingroup$

I guess this is more probable to add a clarification in the riddle's body rather than be accepted as an answer.

$5 + 5 + 5 \le 555$

Improve this answer
$\endgroup$
1
  • 1
    $\begingroup$ You have 550 instead of 555, but otherwise, yes this could be a solution. $\endgroup$
    – Ryan Leach
    Commented Oct 16, 2018 at 7:40
2
$\begingroup$

one more solution I would like to post,
enter image description here

Improve this answer
$\endgroup$
4
  • 1
    $\begingroup$ Clever but not what I'm looking for :D $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 7:44
  • 4
    $\begingroup$ I thought of that, but "5" is not even an equation $\endgroup$
    – George Menoutis
    Commented Oct 16, 2018 at 7:44
  • 1
    $\begingroup$ Please avoid posting separate, short answers; instead, merge them together. $\endgroup$
    – TheSimpliFire
    Commented Oct 16, 2018 at 7:47
  • 4
    $\begingroup$ @TheSimpliFire .. two different approach to solve a problem can be two different answers.. it's not one answer, it's just different.. $\endgroup$
    – Naeem Shaikh
    Commented Oct 16, 2018 at 11:33
2
$\begingroup$

Can it be like this ?? I use one line as a border.

Improve this answer
$\endgroup$
5
  • 1
    $\begingroup$ But that won't be a "valid" equation right? I mean you still have unused number outside of the border :D $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 8:19
  • $\begingroup$ @KevinL So? Often you'll see page numbers nearby an equation... do those have to participate in the equation too? $\endgroup$
    – Sneftel
    Commented Oct 16, 2018 at 10:00
  • $\begingroup$ @Sneftel Interesting find, but unfortunately, it won't be part of the equation :D $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 13:07
  • $\begingroup$ @KevinL That's my point. If it's okay to disregard page numbers, it's okay to disregard stuff outside the box. $\endgroup$
    – Sneftel
    Commented Oct 16, 2018 at 13:39
  • $\begingroup$ @Sneftel True, well I guess this may count but at the end, the highest voted answer will get the tick :D $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 13:39
1
$\begingroup$

Here's my attempt:

Equation Modified

So you end up with 5 + 55 = 5 + 55

Improve this answer
$\endgroup$
1
$\begingroup$ 

  5   
+   55  = 555
Using our base 10 (decimal) system when doing sums. So the first 5 would become 500, the second 50, and the last is the unit.

Improve this answer
$\endgroup$
2
  • 1
    $\begingroup$ Nice answer mate :D $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 14:04
  • $\begingroup$ This is cool and all, but how is this one line? $\endgroup$
    – Ryan Leach
    Commented Oct 18, 2018 at 3:37
0
$\begingroup$

Probably not the answer since i added a dot below the added line.
5 + 5 + 5 != 555

Improve this answer
$\endgroup$
0
$\begingroup$

Fine, many creative answers are provided. Here are my two cents based on Xhienne's answer-

It is true to say that 5 + 5 + 5 = 55 / 5, in a number system - with base 6

As,

,LHS is 15 (base 6) = 11 ( base 10) and RHS is 55 / 5 (base 6) = 11 (base 6) resulting in 11 on both the sides!

Improve this answer
$\endgroup$
1
  • $\begingroup$ Sorry, but your notation is wrong and painful to read. Also, if you introduce different bases, several other solutions arise. For example $5_{10}+5_{10}+5_{10}={15}_{10}={11}_{14}$ $\endgroup$
    – elias
    Commented Oct 17, 2018 at 6:11
-1
$\begingroup$

Results in the following equation:

5 + 5 + 5 ≠ 555

Improve this answer
$\endgroup$
2
  • 2
    $\begingroup$ No crossing the equal sign :D $\endgroup$
    – Kevin L
    Commented Oct 16, 2018 at 13:30
  • $\begingroup$ Oops, didn't see that. I guess when I read Notes and Clarification I thought it was an optional read, and as I was so focused on providing "the obvious answer" I didn't even notice. My bad $\endgroup$
    – AterNyctos
    Commented Oct 17, 2018 at 13:03

Not the answer you're looking for? Browse other questions tagged or ask your own question.