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Puzzle solvers, try your hand at these. I looked at some search strings from people wandering in here looking for answers, and tried to guess what puzzles the searchers were trying to find solutions to.

1. Math puzzle Combine 1, 5, 6, 7 to make… I assume 24? I don’t see an answer. Other puzzlers? Do you think using factorial should be allowed? (then I’ve got 7!/[5(6+1)] )
2. All factors of 90: 1, 2, 3, 5, 6, 9, 10, 15, 18, 30, 45, 90. You could divide each number, 1 through 9 into 90, and then include it if it goes in evenly, and then ‘partner’ each of those factors with a larger one: 90/9 = 10, 90/6 = 15 , and so on. Or you could note that 90 = 213251 and review the logic in this post.

3. Distance formula puzzle. Oh, there are lots of those. I like this one: How far is it as the crow flies from the front upper left corner of a 10x10x10 room to the back lower right corner? Make them use it twice, help them generalize something a little bit neat, if you have time.

I have some other really neat crossing a room puzzles. Maybe I will put one up soon. Anyone else have favorites?
4. Puzzle 5 25 243 1024. Hm. These are all powers of a single prime, they are ascending, but I don’t see the sequence. Any help out there?

5. jbl problems? What’s jbl?

1. October 2, 2006 pm31 12:48 pm 12:48 pm

To make 24, how about 5*6 + 1 – 7?

In a previous post on searches (https://jd2718.wordpress.com/2006/08/19/and-your-question-is/), you said the question was to combine 1, 5, 6, 7 to make 21. The answer is given by a/(b – c/d), for a suitable choice of a, b, c, and d!

For puzzle 4, we have 5 = 5^1, 25 = 5^2, 243 = 3^5, 1024 = 4^5, so maybe the next number is 5^5 = 3125? That seems a little tenuous, but sometimes sequence puzzles are like that!

A nice factor puzzle is to calculate the sum of the factors of various numbers of the form 4n + 3. Then ask: why is the sum always divisible by 4?

2. October 2, 2006 pm31 5:12 pm 5:12 pm

oops. almost too easy. it is a persistent search, though less so than 3,3,8,8. maybe they want us to make a different number?

tenuous, but better than anything I noticed.

nice