Can You Solve These 2 Missing Number Riddles?

• Sentenza
In summary: Basically, the inputs, outputs, and functions were all fair game, so brute force was the only way I could think of to hack it. And sometimes, you can sort of know in advance that it's the only way-- like when dealing with primes, which don't have a nice mathematical formula for solving...

Sentenza

I have been looking for hours... pfff...

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These are kind of silly, since they probably have dozens of possible solutions-- there aren't any stated rules, it's just whatever makes sense to you. Here's some quickie answers I got:

Sentenza said:
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One answer could be 1725. If upper-left is A, lower-left is B, upper right is C, and lower-right is D, then you could have: |C-(|2A-2B|^D)|

Sentenza said:
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I get 24-- if the labels are A, B, C (leftmost-to-rightmost), then one formula could be A+2B+2C+1. oops, should be 18, not 24[/edit]

DaveE

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davee123 said:
I get 24-- if the labels are A, B, C (leftmost-to-rightmost), then one formula could be A+2B+2C+1.
Shouldn't that be
18
?

jimmysnyder said:
Shouldn't that be
18
?

Oops, yep, apparently there was a bug in my math.

DaveE

Ok, some more info... You can only use the numbers in the riddle!

Sentenza said:

Difference in right two - difference in left two? So -6?

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K.J.Healey said:
Difference in right two - difference in left two? So -6?
If you use absolute differences you get 6.

jimmysnyder said:
If you use absolute differences you get 6.

I found this too... But it's wrong... (a friend of mine gave me the riddles)

For the second one 18 is wrong. He said you have to use squares...

Sentenza said:

I have been looking for hours... pfff...
Well, looks like you've found them both (the number riddles that were missing).

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Sentenza said:
I found this too... But it's wrong... (a friend of mine gave me the riddles).
I can understand you saying that it is not the number that your friend was thinking of, but why do you say it is wrong? It meets all the conditions of the puzzle. For one thing, you should add all the conditions to the puzzle at the outset and not hand them out piecemeal. For another, you should add an extra condition to this puzzle: If the puzzle has more than one solution, then only the one my friend is thinking of counts.

I think the friend is handing out the conditions piecemeal.

Gokul43201 said:
I think the friend is handing out the conditions piecemeal.

Yeah, the friend is inaccurate to declare the answer as wrong. Note that "He said you have to use squares" in the 2nd problem, and yet there isn't even a number 2 in the 2nd drawing. So raising something to the 2nd power is using a non-existent number already. You could admittedly GET a 2 if you do a 7-5, but then you've used up a 7 and 5, and can't get a 20 using only 2 and 6. And if you allow using numbers multiple times, then you could say that my earlier answer was correct by rewriting it:
A+B+B+C+C+(A/A)
.

I wrote a program a while back to solve things like these that goes through all the permutations of multiplication, addition, subtraction, division, powers, and modulus-- maybe I can tweak it to show all the possible solutions... Hmmm...

Ok, my original program worked for 4 input numbers, so I could verify that using addition, subtraction, multiplication, division, powers, logs, and modulus, and using each "outlying number" only once, that these are the available solutions for the 1st problem (assuming upper-left is A, lower-left is B, upper-right is C, lower-right is D):

(((B-A)%C)+D)
(D-((A-B)%C))
(D+((B-A)%C))
(((D%C)+B)-A)
(((D%C)+B)%A)
((B+(D%C))-A)
((B+(D%C))%A)
(((D%C)-A)+B)
(B+((D%C)-A))
(B%((D%C)-A))
(B-(A-(D%C)))
(B%(A-(D%C)))
(((A+B)+D)%C)
(((B+A)+D)%C)
(((B-A)+D)%C)
((D+(A+B))%C)
((D-(A-B))%C)
((D+(B+A))%C)
((D+(B-A))%C)
(((A+D)+B)%C)
(((D+A)+B)%C)
(((D-A)+B)%C)
((B+(A+D))%C)
((B-(A-D))%C)
((B%(A-D))%C)
((B+(D+A))%C)
((B+(D-A))%C)
((B%(D-A))%C)
(((B+D)+A)%C)
(((B+D)-A)%C)
(((B+D)%A)%C)
(((D+B)+A)%C)
(((D+B)-A)%C)
(((D+B)%A)%C)
((A+(B+D))%C)
((A+(D+B))%C)

Obviously that doesn't include absolute value, trig functions, factorials, "square", "square root", "cube", "cube root", up-arrow notation, Choose, etc. So that's examining 32,928 possible formulas. If you included a "reasonable" amount of the other functions, it'd be on the order of 5 octillion possible formulas (really infinite), so I decided to skip that.
[/edit]

DaveE

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davee123 said:
I wrote a program a while back to solve things like these that goes through all the permutations of multiplication, addition, subtraction, division, powers, and modulus-- maybe I can tweak it to show all the possible solutions...
Whe I first saw a bunch of Sengupta's cryptarithms, I was thinking about exactly this: that it wouldn't take too long to write a program (and much less time to run it) to wade through the 9! or so possibilities for all of those puzzles. Next, I wondered if that wasn't exactly what you had done.

Gokul43201 said:
Whe I first saw a bunch of Sengupta's cryptarithms, I was thinking about exactly this: that it wouldn't take too long to write a program (and much less time to run it) to wade through the 9! or so possibilities for all of those puzzles. Next, I wondered if that wasn't exactly what you had done.

Yeah, depending on the question, sometimes I'll brute force my way through. But usually I'll try and see what mathemagical tricks I can use before I resort to that. The permutations listed above were actually for a much trickier problem:

Basically, the inputs, outputs, and functions were all fair game, so brute force was the only way I could think of to hack it. And sometimes, you can sort of know in advance that it's the only way-- like when dealing with primes, which don't have a nice mathematical formula for solving them.

DaveE

Probably a stupid question, but what is % ? (i know it's the symbol for percentage, but what do you use it for here?)

Sentenza said:
Probably a stupid question, but what is % ? (i know it's the symbol for percentage, but what do you use it for here?)

That's the modulus function-- it's basically the "remainder" function. So 12 % 5 = 2, 33 % 41 = 33, 11 % 2.5 = 1, etc.

DaveE

davee123 said:
That's the modulus function-- it's basically the "remainder" function. So 12 % 5 = 2, 33 % 41 = 33, 11 % 2.5 = 1, etc.

DaveE

Thanks, I know it as 'rest' :)

He said I was very close with "the difference between the sum of the left numbers and the sum of the right numbers" ... It has to be something this easy...

(I hope you understand, I'm dutch-speaking ;) )

I got the one with the triangles

A=bottom left, B=top, C=bottom right

(A^2+C^2) - B = middle

Sentenza said:

The first one could be:

Zero. You can make each of the five numbers by adding or subtracting two or more of the others

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Soca fo so said:
The first one could be:

Zero. You can make each of the five numbers by adding or subtracting two or more of the others

It's the sum of the even numbers - the sum of the odd numbers

That stupid...

1. What are the rules for solving these 2 missing number riddles?

The rules for solving these riddles vary depending on the specific riddle, but in general, you will be given a series of numbers or symbols and will need to use logic and pattern recognition to determine the missing numbers. You may also need to use basic math operations like addition, subtraction, multiplication, or division to solve the riddles.

2. How difficult are these 2 missing number riddles?

The difficulty of these riddles can vary greatly. Some may be relatively easy and straightforward, while others may require more advanced logic and math skills. It ultimately depends on the specific riddle and your own problem-solving abilities.

3. Can you give an example of a 2 missing number riddle?

One example of a 2 missing number riddle is: 4, 9, __, 25, __. The missing numbers in this sequence are 16 and 36, as each number is the square of the previous number (2^2 = 4, 3^2 = 9, 4^2 = 16, 5^2 = 25, 6^2 = 36).

4. Is there a specific strategy for solving these 2 missing number riddles?

There is no one specific strategy for solving these riddles, as each one may require a different approach. However, some general tips for solving number riddles include looking for patterns, using basic math operations, and testing different combinations until you find the correct answer.

5. Can these 2 missing number riddles have multiple solutions?

In most cases, these riddles are designed to have a single, unique solution. However, there may be rare instances where a riddle could have multiple solutions if there are multiple patterns or logical sequences that could be applied to the given sequence of numbers or symbols.