Posted - 11/06/2011 : 16:27:03 Using 6, 1, 5, 2 you have to generate any of the following numbers: 74, 89, 91.

The rules are as follow:

•you have to use the initial numbers 6, 1, 5 and 2 only ONCE •you can use any math operation: addition, multiplication, substraction, division, square root, power, factorial •you can combine the initial numbers to generate other numbers: i.e. 61, 16, 52, 25, 15, etc. that may help you

Example on how to generate •32: 6^2-5+1 •100: sqrt(16) x 5^2 •28: (6 x 5) - (2 x 1) •86: 61 + 25

Any help you can provide is much appreciated.

4 L A T E S T R E P L I E S (Newest First)

the_hill1962

Posted - 11/11/2011 : 09:59:36 That is true. The poster did not even state any combinations that he/she tried. Anyway, let me ask about this type of problem since you so kindly replied to my post. Is there any way to solve this by a procedure other than guess and check? The way I would try to solve it is to spend some time writing a program on a computer to start going through all the combinations. I haven't calculated the number of combinations it would take to try them all---I think it would be quite a few! Nor do I have any idea if I could even write such a program... I am sure there is a way to calculate the number of combinations of "Using 6, 1, 5, 2..." but since I am not that adept at statistics, I wouldn't know how to calculate it. Is the calculation hard? If not, then would you help me calculate it?

quote:Originally posted by Subhotosh Khan

quote:Originally posted by the_hill1962

This type of problem is a puzzle and, in my opinion, is not something that teaches or tests any math concept per se. Sure, you are using basic math in order to do the problem but solving it is just mere trial and error. Well, there are some obvious combinations that wouldn't be tried and thus maybe one can state that is a math concept that is being learned or tested... Subhotosh: Yes, it is irritating that people post the same problem on multiple sites. However, when you think about it, isn't that what we do on the Internet when we 'search'? Search engines pull up multiple sites and a person goes to more than one site (hopefully) to research and get information.

However, when student put-up problems to be solved - without an iota of original work attached to it - it smells too much like "cheating".

Subhotosh Khan

Posted - 11/10/2011 : 10:38:39

quote:Originally posted by the_hill1962

This type of problem is a puzzle and, in my opinion, is not something that teaches or tests any math concept per se. Sure, you are using basic math in order to do the problem but solving it is just mere trial and error. Well, there are some obvious combinations that wouldn't be tried and thus maybe one can state that is a math concept that is being learned or tested... Subhotosh: Yes, it is irritating that people post the same problem on multiple sites. However, when you think about it, isn't that what we do on the Internet when we 'search'? Search engines pull up multiple sites and a person goes to more than one site (hopefully) to research and get information.

However, when student put-up problems to be solved - without an iota of original work attached to it - it smells too much like "cheating".

the_hill1962

Posted - 11/09/2011 : 10:23:04 This type of problem is a puzzle and, in my opinion, is not something that teaches or tests any math concept per se. Sure, you are using basic math in order to do the problem but solving it is just mere trial and error. Well, there are some obvious combinations that wouldn't be tried and thus maybe one can state that is a math concept that is being learned or tested... Subhotosh: Yes, it is irritating that people post the same problem on multiple sites. However, when you think about it, isn't that what we do on the Internet when we 'search'? Search engines pull up multiple sites and a person goes to more than one site (hopefully) to research and get information.

Subhotosh Khan

Posted - 11/06/2011 : 21:17:47

quote:Originally posted by criss72

Using 6, 1, 5, 2 you have to generate any of the following numbers: 74, 89, 91.

The rules are as follow:

•you have to use the initial numbers 6, 1, 5 and 2 only ONCE •you can use any math operation: addition, multiplication, substraction, division, square root, power, factorial •you can combine the initial numbers to generate other numbers: i.e. 61, 16, 52, 25, 15, etc. that may help you

Example on how to generate •32: 6^2-5+1 •100: sqrt(16) x 5^2 •28: (6 x 5) - (2 x 1) •86: 61 + 25