What is the missing product in this sequence of equations?

  • Thread starter Greg Bernhardt
  • Start date
In summary, the problem is that when you add the numbers in the top row, the second number in the row below it must be subtracted. If the second number is 6, then the equation for the number 27 is 2 less than 10 or 8. If the second number is 7, then the equation for the number 27 is 2 less than 11 or 6.
  • #1
19,407
9,949
If

7x7=4
11x7=6
13x11=6

Then

27x28=?
 
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  • #2
Originally posted by Robert Zaleski
8

I'm impressed, Zaleski. Explain
 
  • #3
oops your answer changed from 8 to 6!

I still believe you are right, and understand the problem,
so please explain
 
  • #4
Originally, I posted 8. Here's how I arrived at that number.

The difference between prime number 23 and prime number 19 is 4.
The difference between prime number 29 and 23 is 6. Adding 6+4 you get 10. The number your looking for is 27, which is 2 less than 10 or the number 8. I think the number 6 may be another way of looking at it, i.e., 27-23=4, 29-27=2, 4+2=6.
 
  • #5
Thanks RZ, I don't understand you but I'm still impressed:smile:

this problem has a nice open-ended character----maybe we
will be getting further attempts!
 
  • #6
6

it's the amount of 'e's in the number

seven (2 'e's) x seven (2 'e's) = 4
eleven (3 'e's) x seven (2 'e's) = 6
thirteen (2 'e's) x eleven (3 'e's) = 6

twenty-seven (3 'e's) x twenty-eight (2 'e's) = 6
 
  • #7
7x7=4

11x7=6

13x11=6

17x13=6

19x17=6

23x19=10

29x23=8

31x29=



Your subtracting the second number in a top row by the first number in the row below it, i.e., 11-7=4, 13-7=6, 17-11=6, etc.

Therefore, 27x28=8 (27-19=8)
 
  • #8
I just noticed, this isn't a brain teaser, it's a Brian teaser.
Too bad I don't know anyone called Brian. =P
 
  • #9
RZ -- i thought of that too, but what you did assumes that each "equation" canNOT be done independently, which doesn't seem right. you should be able to do these equations by themselves.

in other words, the answer you get depends on the previous equations you have used.

look:
7x7=4

11x7=6

13x11=6

17x13=6

19x17=6

23x19=10

[27x28 should come right here, but it gets "skipped over" according to your rules (27x28 does not exist in your scheme)]

29x23=8


i think Asimir gets the point
 
  • #10
Well, we gave it a try Brum. Asimir answer looks like a winner.
 
  • #11
Perhaps each number in the left side of the equation represents an alternate number


7x7=4 this is really: 2 x 2 = 4 so 7 = 2

11x7=6 if 7 = 2 then 6/2 = 3 so 11 = 3

13x11=6 if 11 = 3 then 6/3 = 2 so 13 = 2



Then

27 x 28 = 48


27 ---> 7 + 7 + 13 which is really 2 + 2 + 2 or 6
28 ---> 7 + 7 + 7 + 7 which is really 2 + 2 + 2 + 2 or 8


And 6 x 8 = 48

So then with the substituted numbers 27 x 28 = 48


Hope I didn't make that too complicated!
 
  • #12
I'm impressed reddhawk, how come I didn't come to that idea. I don't think I'd need to post anything now.
 
  • #13
Maybe x isn't an operator at all, but a variable representing that particular digit.

ie.

7x7 -> 747
11x7 -> 1167
13x11 -> 13611

Then

27x28 -> 27?28

So we can consider these not as equations, but as a sequence of numbers.

Sum digits:

747 -> 18
1167 -> 15
13611 -> 12
so 27?28 -> 9

so 27x28 = -10
 
  • #15
Each of the numbered words begins with one of three letters, i.e. ,S, E, or T.
I’ve assigned each letter a number as follows:
S=2
E=3
T=2

Twenty Seven x Twenty Eight
...(2x2)...x...(2x3)= 24
 
  • #16
Wow, I am surpised no one has got this one. I thought there were a bunch of good answers. Well here my try from left field:

7x7

seven -> sev-en = 2 syllables

so 2 x 2 = 4

e-lev-en = 3 syllables

so 3x2 = 6

thirt-teen = 2 syllables

so 2 x 3 = 6

Finally 27x28

twen-ty sev-en = 4 syllables
twen-ty eight = 3 syllables

4 x 3 = 12

12 is my final answer
 
  • #17
dduardo gets the point! Good work everyone else though!
 

1. How is it possible for 7x7 to equal 4?

The equation 7x7=4 is not mathematically possible. It violates the basic rules of multiplication and cannot be solved for any value of x. Therefore, this equation is most likely incorrect or incomplete.

2. Why do the equations seem to have different solutions for the same multiplication?

The equations in this problem are not following a consistent pattern. The first equation follows the rule of multiplying two odd numbers resulting in an odd number, while the other two equations do not. This inconsistency suggests that the equations may be incorrect or incomplete.

3. Is this a trick question or a math puzzle?

Without further context, it is difficult to determine the intention behind these equations. However, based on the inconsistencies and impossibility of some of the solutions, it is likely that this is not a valid math problem. Therefore, it can be considered a trick question or a math puzzle.

4. What could be the correct answers to these equations?

Without any additional information or context, it is impossible to determine the correct answers to these equations. It is possible that the given equations are incorrect or incomplete, and there may be no solution. Alternatively, there may be additional equations or rules that need to be considered in order to find the correct solutions.

5. How can I solve these equations?

As mentioned before, without any further context or information, it is impossible to solve these equations. It is important to first check if the equations follow a logical pattern and if they are mathematically valid. If not, then it is likely that there is no solution. If the equations seem to be valid, then it is necessary to examine any additional rules or equations that may be needed to find the solutions.

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