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Jim M
Lv 6
Jim M asked in Science & MathematicsMathematics · 7 years ago

I am making a largish number fraction Puzzle and need help with numerators?

Background: I was doing some LCD examples and contrived 1/27, 1/37, 1/77, and 1/117 to show that one can't just list multiples. (for 12 and 15 we can list 12,24,,36,48,60 and 15,30,45,60 and easily get the LCD).

I want to solve i/27 + j/37 + k/77 + l/177 = 1. This is what I believe is called a Diophantine Equation (integer solutions and may have more than one solution).

Excel doesn't want to find an answer for me and since I made the puzzle google isn't working for me. I want i,j,k, and l to be reasonable numbers. Best answer to the most reasonable numbers.

since there are 7s in the denominators it seems there should be a bonus for 7s in the numerators.

I intend to put this in a puzzle magazine and will cite you using your yahoo id or any name (I can say to my mother.) you want me to use.

Update:

Thank you DW. It should be 117. Then the LCD is 999,999.

To wit, solve for integers i,j,k,l i/27 + j/37 + k/77 + l/117 = 1.

(It also occured to me that 2, or a half, or a third would also work.

Update 2:

I am running a program. It gave the answer:

3/27 + 0/37 + 77/77 - 13/117 = 1.

Using 77/77 and 0/37 are so boring I can't use them in a puzzle. And notice that 3/27 = -13/117, so that is boring too.

1 Answer

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  • DWRead
    Lv 7
    7 years ago

    Are you using 117 or 177? You list both.

    Factor each denominator into powers of primes

    27 = 3³

    37 = 37

    77 = 7×11

    177 = 3×59

    Least common denominator = 3³×37×7×11×59 = 4,538,457

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