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Logic Level 1

This calculation will tell you who you really are?

Pick any integral number between 1 to 9 inclusive.

Now multiply it by 3 3 .

Add 3 3 .

Now again multiply it by 3 3 .

You will get two digits, now add them. now this number will tell who you really are

1. Kind 2. Gentle 3. Honest 4. Caring 5. Reliable 6. Adventurous 7. Romantic 8. Faithful 9. Somewhat Stupid 10. Protective \begin{aligned} &\text{1. }& \text{ Kind }\\ &\text{2. }& \text{ Gentle }\\ &\text{3. }& \text{ Honest }\\ &\text{4. }& \text{ Caring }\\ &\text{5. }& \text{ Reliable }\\ &\text{6. }& \text{ Adventurous }\\ &\text{7. }& \text{ Romantic }\\ &\text{8. }& \text{ Faithful }\\ &\text{9. }& \text{ Somewhat Stupid }\\ &\text{10. }& \text{ Protective }\\ \end{aligned}

You have to enter the sum of digits obtained. No offense.


The answer is 9.

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14 solutions

Let n n be the chosen integer such that 1 n 9. 1 \le n \le 9. Then the given operations leave us with the value 3 ( 3 n + 3 ) = 9 ( n + 1 ) , 3(3n + 3) = 9(n + 1), which, given the possible values of n n , will be a 2-digit positive integer divisible by 9. 9. But the sum of the digits of any such integer is 9 , 9, and so anyone who answers this question is .....

Nice one, @Tanishq Varshney .:D

Moderator note:

Cute one, Tanishq Varshney!

BTW only 72% people got it right

Arulx Z - 6 years, 1 month ago

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lol ...... ;)

Madhukar Thalore - 6 years ago

Hahahaha Thumbs up @Tanishq Varshney

A Former Brilliant Member - 6 years, 1 month ago

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My friend gave me this problem and the qualities mentioned were different. U know what i mean , but it was a hilarious encounter.

Tanishq Varshney - 6 years, 1 month ago

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Hai its crct

Raahul Rajakumar - 5 years, 10 months ago

Haha...yup!! Good one, though:D

A Former Brilliant Member - 6 years, 1 month ago

This was rigged, was it?

Derek Guo - 6 years, 1 month ago

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Yes, mathematically rigged ^^'

Maddie Anderson - 6 years, 1 month ago

oooooooooo

ash ash - 5 years, 8 months ago

your head !!!!!!!!!!!!

ash ash - 5 years, 8 months ago

But how would you prove (for completeness?) that the sum of the two digits must add up to nine? Though i do see that for n ranging from 1 to 9 produces multiples of 9 and hence the sum adds up to nine (intuition, as the tens digit increases by 1 the units digit decreases by 1 and hence sum is constant) i cannot think of a way to prove this, would you help?

Jeffrey Li - 5 years, 6 months ago

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This is the "divisibility by 9 9 " rule, a general proof of which is as follows:

Suppose we have a ( k + 1 ) (k + 1) -digit number N = a k a k 1 a k 2 . . . . a 1 a 0 N = \overline{a_{k}a_{k-1}a_{k-2}....a_{1}a_{0}} where 1 a k 9 1 \le a_{k} \le 9 and 0 a i 9 0 \le a_{i} \le 9 for 0 i k 1. 0 \le i \le k - 1.

We can then write the numerical value of N N as

N = a k 1 0 k + a k 1 1 0 k 1 + . . . . + a 1 1 0 1 + a 0 1 0 0 . N = a_{k}*10^{k} + a_{k-1}*10^{k-1} + .... + a_{1}*10^{1} + a_{0}*10^{0}.

Now look at N ( m o d 9 ) . N \pmod{9}. Since 10 1 ( m o d 9 ) , 10 \equiv 1 \pmod{9}, we know that 1 0 j 1 j 1 ( m o d 9 ) , 10^{j} \equiv 1^{j} \equiv 1 \pmod{9}, and so

N ( m o d 9 ) a k 1 + a k 1 1 + . . . . + a 1 1 + a 0 1 ( m o d 9 ) , N \pmod{9} \equiv a_{k}*1 + a_{k-1}*1 + .... + a_{1}*1 + a_{0}*1 \pmod{9},

which is precisely the digit sum of N N modulo 9 9 . Thus if any integer N N is divisible by 9 9 , so too will its digit sum be divisible by 9 9 , (and visa versa).

Brian Charlesworth - 5 years, 6 months ago
Alex Li
Apr 27, 2015

Wait, so if I choose 4 3 \frac{4}{3} then I am honest?

pretty clever, BTW i edited to take only integers between 1 and 9.

Tanishq Varshney - 6 years, 1 month ago

Haha... honest people play by the rules. Picking 4/3 would be very contradictory, as it would prove that the system says you're honest only when you're dishonest. Actually, it would be no more contradictory than if you picked an integer 1 to 9 because you would be intelligent for solving the problem, but the system would say you are stupid.

Jared Jones - 6 years ago

Integral number

Anchala Elsa - 6 years, 1 month ago

Alex, the question asks you to choose an integer.

Noel Lo - 6 years, 1 month ago

No it has to be a whole number

Abby Ellison - 5 years, 11 months ago
Tea Quack
May 22, 2015

Let the number you choose be x x , 3 x + 3 3x+3 is a multiple of three. So, 3 ( 3 x + 3 ) 3(3x+3) is a multiple of 3 3 3*3 .So, the sum of its digit is always

9 \LARGE\color{#20A900}9

Couldnt have said it better myself. Its all about the number play. More specifically, any time you add the digits of a multiple of nine, like what is achieved when you multiply 3 by itself, the digits will always add up to 9. Rule of 9s

Alex Hirt - 5 years, 10 months ago
Deborah Jennings
Jul 9, 2015

That's not very nice but true at the same time..

Ppk K
Feb 12, 2017

So when we choose a number between 0-9, the given operations tend to make the answer 9 and ...... as we get the equation 3(3n+3)=9n+9=9(n+1) which tends to make it a multiple of 9 and hence the answer always is 9....

Kaitlyn Collantes
Sep 27, 2015

look at the "No offense" part at the bottom, see the most offensive #, and click.

Haha... I am STUPID??.. cool! :D

Eric Washburn
Aug 13, 2015

"Relaible" is spelled wrong. Who's stupid now?

Laryn Skinner
Aug 3, 2015

Very sneaky slow clapping

Jaswinder Singh
Jul 7, 2015

Great mind

Alex Li
Jul 1, 2015

The only important part of the problem is the last sentence. This implies that the problem will end up being some sort of insult. Since only 9 can be considered a insult, 9 is the correct answer.

Anubhav Balodhi
Jun 8, 2015

An intelligent person always knows that he is stupid :-b cute question...

Madhukar Thalore
May 31, 2015

you will always get 9 ;)

Noel Lo
Apr 28, 2015

Seriously...

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