- #1

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If

7x7=4

11x7=6

13x11=6

Then

27x28=?

7x7=4

11x7=6

13x11=6

Then

27x28=?

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- Thread starter Greg Bernhardt
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- #1

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If

7x7=4

11x7=6

13x11=6

Then

27x28=?

7x7=4

11x7=6

13x11=6

Then

27x28=?

- #2

marcus

Science Advisor

Gold Member

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Originally posted by Robert Zaleski

8

I'm impressed, Zaleski. Explain

- #3

marcus

Science Advisor

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I still believe you are right, and understand the problem,

so please explain

- #4

Robert Zaleski

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

marcus

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this problem has a nice open-ended character----maybe we

will be getting further attempts!

- #6

Asimir

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

Robert Zaleski

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

Asimir

Too bad I don't know anyone called Brian. =P

- #9

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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

29x23=8

i think Asimir gets the point

- #10

Robert Zaleski

Well, we gave it a try Brum. Asimir answer looks like a winner.

- #11

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- 0

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

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- #13

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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

- #14

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Hint #1: Think about how the numbers are spelled.

- #15

Robert Zaleski

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

dduardo

Staff Emeritus

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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

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dduardo gets the point! Good work everyone else though!

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