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Home » Math and Logic Problem Exchange » Figure Logic 1 from September 1999 issue

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10/23/2016 11:49:39 AM

mark1016
mark1016
Posts: 1
Hello.

I know this is a shot in the dark but, my daughter was assigned a logic problem for extra credit (high school math). The figure logic puzzle is from the September 199 issue of Math Puzzles and Logic Problems. Neither she nor I have done one of these before and they seem, well...impossible...I feel like if she knew a few of the numbers she might be able to do the puzzle. Or, if someone could give some tips on how to do these that would be great too.

Mark

10/24/2016 11:30:21 PM

Josh
Josh
Posts: 170
mark1016 wrote:
Hello.

I know this is a shot in the dark but, my daughter was assigned a logic problem for extra credit (high school math). The figure logic puzzle is from the September 199 issue of Math Puzzles and Logic Problems. Neither she nor I have done one of these before and they seem, well...impossible...I feel like if she knew a few of the numbers she might be able to do the puzzle. Or, if someone could give some tips on how to do these that would be great too.

Mark



Hi Mark,

I have a pretty deep stack of that particular publication, but one of the digits was missing in your year. Can you clarify which year? I can provide Figure Logic solving tips in the context of the actual puzzle presented.

EDIT: Re-read the subject and saw it said Figure Logic 1 in September 1999, so sorry, saw you included that! Will dig out the issue and provide some tips tomorrow.

EDIT 2: I actually don't have it! I have September 1998 but not 1999. If you're able to post a picture/scan, happy to provide solving tips to get her started.

Josh
edited by jjofriends on 10/24/2016
edited by jjofriends on 10/24/2016

11/1/2016 12:10:06 PM

ThrillerFan
ThrillerFan
Posts: 6
I can't speak for having that particular puzzle, but here are some tips for solving figure logics:

1) Look for 2-digit answers first. If a 2-digit number is double, triple, quadruple, or even 9 times that of another answer, it eliminates possibilities of what that smaller number is. Like if 14 across is 2 digits, and says 5 times 9 across, then you know the first digit of 9 across is a 1 because 20*5 is too big, would be 3 digits.

2) Remember that no number starts with a 0. So if a later digit in a number is also the first digit of another number, that digit can't be 0.

3) You may not be able to fill in the entire answer at one time. Like item 1 above, you could figure out that 9 across starts with a 1, but you don't know the last digit. Go ahead and fill in the 1.

4) Always use the tricks for odd and even numbers. For addition, if you are adding 2 odds or 2 evens, you get an even. If you have one of each, it's odd. For multiplication, all products are even except where both numbers you are multiplying are odd. So if a clue is the product of two other numbers, and you already know it is odd from a crossing number, then both the other numbers must be odd as well.

5) Connect multiple clues together. If 1 across is 2 digits and double that of 5 across, and 5 across is double that of 30 down, then 1 across is 4 times 30 down, so 30 down can be at most 24.

6) Always look for cases where you have a different number of digits in a sum or difference. For example, if 5 down is 4 digits, and it's the sum of two other numbers that are only 3 digits, then it must start with a 1, and can be at most 1998 (999 + 999).

7. Lastly, some clues will be a specific number more or less than another number, like say, if 15-Across is "8 less than 9 Down", once you have the last digit of one of them, you can enter the last digit of the other. In this case, if from a crossing number, you figure out the last digit of 15 across is a 4, then you know 9 down ends in a 2, even though you may not have the rest of 9-down.


As you get a few individual digits this way, eventually you'll have an entire number filled in, and it's from there that things at least start to get easier.

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