Find the missing number (triangle)
Find the missing number (triangle)
Find the missing number (triangle)
Options:
9
8
7
10
Please write the logic also.
Also are you sure your options for the answer are right? Did you get the options with the question?
– nikki
Aug 26 at 8:01
2 Answers
2
Answer:
$$?=10.$$
$$$$
Explanation:
Suppose that
we have an equilateral triangle $Delta rm ABC$: 
Then,
the number in the middle of the triangle (say, $rm M$) is created from the formula: $$rm M = (Itimes II) + III - 10.$$
$$$$
Examples:
$$beginalign 33 &= (5times 7) + 8 - 10 \ &= 35 -2 \ &= 33;colorgreencheckmark tag1 endalign$$
$$beginalign 63 &= (7times 9) + 10 - 10 \ &= 63 + 0 \ &= 63;colorgreencheckmarktag2endalign$$
And last but not least...
$$beginalign132 &= (12times 11):+:? - 10 \ &= 132:+:? - 10 \ &= 122:+:? \ &Downarrow \ ?&=132-122 \ &= 10.tag3endalign$$
(+1) nice. As a challenge, seeing as you love mathjax perhaps you could try producing the triangle with it? ;)
– TheSimpliFire
Aug 26 at 13:09
@TheSimpliFire if you can actually do that, that would be pretty cool, because I have no idea, hahah :P
– user477343
Aug 26 at 13:23
Found the $LaTeX$ code: tex.stackexchange.com/questions/244376/drawing-a-triangle
– TheSimpliFire
Aug 26 at 13:54
Oh my... that is beautiful! But unfortunately, when I tried it, it does not work... Thus far, my best bet is the following: $$LARGEtriangle$$ Since it contains 'document' commands, I am pretty sure this can only be done when writing an actual document (paper) using $LaTeX$, but this theory is a little debunked because the user in the link can format it on the TeX site... perhaps Puzzling alone is culpable, because when I type it, there is an "unknown environment 'document'".
– user477343
Aug 26 at 21:50
Alternative answer:
Pattern:
The fractional part of $fractextnumber in triangletextnumber left of triangle$ is less than $frac12$.
Hence the answer is
$10$
as
$$frac1327=18.85cdots,quadfrac1328=16.5,quadfrac1329=14.66cdots,quadfrac13210=13.2$$
Examples:
$$frac338=4.125,quadfrac6310=6.3$$
Talking about $LaTeX$, go here!!
– user477343
Sep 1 at 5:09
@user477343 Nice! Feel free to check out my mathmatical fortnight challenge on my profile :)
– TheSimpliFire
Sep 1 at 18:22
Can that be found in your blog? Edit: Oh wait, nevermind. The $LaTeX$ just needed to load, hahah :P
– user477343
Sep 1 at 18:24
@user477343 THat'll have to wait until 16/09 (when it ends). But it's there on my SE profile
– TheSimpliFire
Sep 1 at 18:24
Hmm... let's get @Cleo :D
– user477343
Sep 1 at 18:25
By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.
Hello and welcome to PSE. Did you come up with this puzzle yourself or is it copied from elsewhere? If it's not your you should provide the source of the puzzle.
– rhsquared
Aug 26 at 7:32