Just One Line! Really? [closed]

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 :

• Are you sure you didn't mean "= 550"? – Alconja Oct 16 '18 at 4:46
• Nope, this is a new one :D @Alconja – Kevin L Oct 16 '18 at 4:52
• Does the line need to be perfectly straight like it did in the 550 question? – Arpeggio Oct 16 '18 at 5:36
• @RyanTheLeach it doesn't need to be "an axis aligned to the equal sign" :D – Kevin L Oct 16 '18 at 7:47
• @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 – Kevin L Oct 16 '18 at 8:04

15 Answers

This equation is true

... in base 14:

$$5 + 5 + 5 = 55 / 5$$

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

• A really creative answer (+1) :D – Kevin L Oct 16 '18 at 8:43
• this one is a nice answer really – Shahriar Mahmud Sajid Oct 16 '18 at 8:46
• 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 ;-) – xhienne Oct 16 '18 at 8:57
• puzzling is for fun! You can see some really weird solutions around... – George Menoutis Oct 16 '18 at 11:09
• @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. – El-Guest Oct 16 '18 at 15:14

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

Or using correction fluid :

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.

• In my opinion, whoever upvotes this answer should also upvote Naeem Shaikh's answer. – xhienne Oct 16 '18 at 12:57
• @xhienne: My answer is a play on the wording "one line", so I would say that it is a succinctly different solution. – M.Herzkamp Oct 16 '18 at 13:03
• Oh, you are right, sorry I missed the subtlety of your answer. – xhienne Oct 16 '18 at 13:05

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

(Line is curvy)

• Very clever but that would be too easy. Nevertheless, (+1) from me :D – Kevin L Oct 16 '18 at 14:05
• This is the best answer xD $(+1)$ – Mr Pie Oct 17 '18 at 2:42

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:

 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).

• Welcome to Puzzling SE! Love the cleverness of this answer and well formatted, keep up the good work! – gabbo1092 Oct 16 '18 at 15:53
• You can argue that the angle line is actually two lines. – Tejas Kale Oct 16 '18 at 16:08
• 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. :) – AnonyTech Oct 16 '18 at 16:11
• Clever one, you could also add one circular line telling : 5+5+5=555° – qq jkztd Oct 16 '18 at 16:15
• this is the best answer so far – Shahriar Mahmud Sajid Oct 17 '18 at 4:28

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

• Nice try but not the intended one :D – Kevin L Oct 16 '18 at 7:44
• 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! – feelinferrety Oct 16 '18 at 16:30

My try!

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

• Yes, this can be the answer but I'm still waiting for others to come up with better ones (+1) :D – Kevin L Oct 16 '18 at 7:44
• Please tell me you have an answer in mind? – Ryan The Leach Oct 16 '18 at 7:46
• @RyanTheLeach Oh I do myself but I'm sure others have even more – Kevin L Oct 16 '18 at 7:46
• @TheSimpliFire I don't understand your solution. The symbol you used means 'equivalence' or 'identical to'. How does that work? – rhsquared Oct 16 '18 at 7:52
• @rhsquared Congruences – TheSimpliFire Oct 16 '18 at 7:54

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

$$5 + 5 + 5 \le 555$$

• You have 550 instead of 555, but otherwise, yes this could be a solution. – Ryan The Leach Oct 16 '18 at 7:40

one more solution I would like to post,

• Clever but not what I'm looking for :D – Kevin L Oct 16 '18 at 7:44
• I thought of that, but "5" is not even an equation – George Menoutis Oct 16 '18 at 7:44
• Please avoid posting separate, short answers; instead, merge them together. – TheSimpliFire Oct 16 '18 at 7:47
• @TheSimpliFire .. two different approach to solve a problem can be two different answers.. it's not one answer, it's just different.. – Naeem Shaikh Oct 16 '18 at 11:33

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

• But that won't be a "valid" equation right? I mean you still have unused number outside of the border :D – Kevin L Oct 16 '18 at 8:19
• @KevinL So? Often you'll see page numbers nearby an equation... do those have to participate in the equation too? – Sneftel Oct 16 '18 at 10:00
• @Sneftel Interesting find, but unfortunately, it won't be part of the equation :D – Kevin L Oct 16 '18 at 13:07
• @KevinL That's my point. If it's okay to disregard page numbers, it's okay to disregard stuff outside the box. – Sneftel Oct 16 '18 at 13:39
• @Sneftel True, well I guess this may count but at the end, the highest voted answer will get the tick :D – Kevin L Oct 16 '18 at 13:39

Here's my attempt:

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

  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.

• Nice answer mate :D – Kevin L Oct 16 '18 at 14:04
• This is cool and all, but how is this one line? – Ryan The Leach Oct 18 '18 at 3:37

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

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!

• Sorry, but your notation is wrong and painful to read. Also, if you introduce different bases, several other solutions arise. For example $5_{10}+5_{10}+5_{10}={15}_{10}={11}_{14}$ – elias Oct 17 '18 at 6:11

Results in the following equation:

5 + 5 + 5 ≠ 555

• No crossing the equal sign :D – Kevin L Oct 16 '18 at 13:30
• 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 – AterNyctos Oct 17 '18 at 13:03