How to identify whether permutation question involves repetition or not

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1) How many three-digit numbers more than 600 can be formed by using the digits $2,3,4,6,7$?



2) How many number greater than a million can be formed with the digits $2,3,0,3,4,2,3$?




How could I distinguish between a repetition and non repetition permutation question?



E.g.: In first question repetition of digits is allowed, but in second repetition is not allowed (e.g. it can't have $3333333$).




Note: Please explain me how can I guess whether a question involves repetition or not,in general not only on this specific question.











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  • 1




    On 1): the first digit must be $6$ or a $7$ (so $2$ choices). For the second and third there are $5$ choices. So $2times5times5$ numbers in total.
    – drhab
    Sep 9 at 17:19










  • @drhab Note: Please explain me how can I guess whether a question involves repetition or not,in general not only on this specific question.I already know how to solve this question.
    – J.Doe
    Sep 9 at 17:21






  • 1




    Sorry, but I cannot really help you with that. Also for me every time I encounter a problem in that context I must wonder: "what exactly is allowed and what is not?" Others will have that too, and it might explain why your question on that has not been answered.
    – drhab
    Sep 9 at 17:23







  • 1




    I suspect that in both questions repetition of digits is not permitted since the questions do not explicitly state that repetition is permitted. In the second exercise, you may use each digit the number of times it appears in the list.
    – N. F. Taussig
    Sep 9 at 17:46






  • 1




    It sounds like you would benefit from reading a more carefully written textbook. It should be the responsibility of the author to make clear whether repetition is permitted. Your request is a result of the failure of the author of your textbook to do that.
    – N. F. Taussig
    Sep 9 at 19:41














up vote
4
down vote

favorite
3













1) How many three-digit numbers more than 600 can be formed by using the digits $2,3,4,6,7$?



2) How many number greater than a million can be formed with the digits $2,3,0,3,4,2,3$?




How could I distinguish between a repetition and non repetition permutation question?



E.g.: In first question repetition of digits is allowed, but in second repetition is not allowed (e.g. it can't have $3333333$).




Note: Please explain me how can I guess whether a question involves repetition or not,in general not only on this specific question.











share|cite|improve this question



















  • 1




    On 1): the first digit must be $6$ or a $7$ (so $2$ choices). For the second and third there are $5$ choices. So $2times5times5$ numbers in total.
    – drhab
    Sep 9 at 17:19










  • @drhab Note: Please explain me how can I guess whether a question involves repetition or not,in general not only on this specific question.I already know how to solve this question.
    – J.Doe
    Sep 9 at 17:21






  • 1




    Sorry, but I cannot really help you with that. Also for me every time I encounter a problem in that context I must wonder: "what exactly is allowed and what is not?" Others will have that too, and it might explain why your question on that has not been answered.
    – drhab
    Sep 9 at 17:23







  • 1




    I suspect that in both questions repetition of digits is not permitted since the questions do not explicitly state that repetition is permitted. In the second exercise, you may use each digit the number of times it appears in the list.
    – N. F. Taussig
    Sep 9 at 17:46






  • 1




    It sounds like you would benefit from reading a more carefully written textbook. It should be the responsibility of the author to make clear whether repetition is permitted. Your request is a result of the failure of the author of your textbook to do that.
    – N. F. Taussig
    Sep 9 at 19:41












up vote
4
down vote

favorite
3









up vote
4
down vote

favorite
3






3






1) How many three-digit numbers more than 600 can be formed by using the digits $2,3,4,6,7$?



2) How many number greater than a million can be formed with the digits $2,3,0,3,4,2,3$?




How could I distinguish between a repetition and non repetition permutation question?



E.g.: In first question repetition of digits is allowed, but in second repetition is not allowed (e.g. it can't have $3333333$).




Note: Please explain me how can I guess whether a question involves repetition or not,in general not only on this specific question.











share|cite|improve this question
















1) How many three-digit numbers more than 600 can be formed by using the digits $2,3,4,6,7$?



2) How many number greater than a million can be formed with the digits $2,3,0,3,4,2,3$?




How could I distinguish between a repetition and non repetition permutation question?



E.g.: In first question repetition of digits is allowed, but in second repetition is not allowed (e.g. it can't have $3333333$).




Note: Please explain me how can I guess whether a question involves repetition or not,in general not only on this specific question.








permutations






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edited Sep 9 at 9:18









Jendrik Stelzner

7,69121137




7,69121137










asked Sep 9 at 9:13









J.Doe

236




236







  • 1




    On 1): the first digit must be $6$ or a $7$ (so $2$ choices). For the second and third there are $5$ choices. So $2times5times5$ numbers in total.
    – drhab
    Sep 9 at 17:19










  • @drhab Note: Please explain me how can I guess whether a question involves repetition or not,in general not only on this specific question.I already know how to solve this question.
    – J.Doe
    Sep 9 at 17:21






  • 1




    Sorry, but I cannot really help you with that. Also for me every time I encounter a problem in that context I must wonder: "what exactly is allowed and what is not?" Others will have that too, and it might explain why your question on that has not been answered.
    – drhab
    Sep 9 at 17:23







  • 1




    I suspect that in both questions repetition of digits is not permitted since the questions do not explicitly state that repetition is permitted. In the second exercise, you may use each digit the number of times it appears in the list.
    – N. F. Taussig
    Sep 9 at 17:46






  • 1




    It sounds like you would benefit from reading a more carefully written textbook. It should be the responsibility of the author to make clear whether repetition is permitted. Your request is a result of the failure of the author of your textbook to do that.
    – N. F. Taussig
    Sep 9 at 19:41












  • 1




    On 1): the first digit must be $6$ or a $7$ (so $2$ choices). For the second and third there are $5$ choices. So $2times5times5$ numbers in total.
    – drhab
    Sep 9 at 17:19










  • @drhab Note: Please explain me how can I guess whether a question involves repetition or not,in general not only on this specific question.I already know how to solve this question.
    – J.Doe
    Sep 9 at 17:21






  • 1




    Sorry, but I cannot really help you with that. Also for me every time I encounter a problem in that context I must wonder: "what exactly is allowed and what is not?" Others will have that too, and it might explain why your question on that has not been answered.
    – drhab
    Sep 9 at 17:23







  • 1




    I suspect that in both questions repetition of digits is not permitted since the questions do not explicitly state that repetition is permitted. In the second exercise, you may use each digit the number of times it appears in the list.
    – N. F. Taussig
    Sep 9 at 17:46






  • 1




    It sounds like you would benefit from reading a more carefully written textbook. It should be the responsibility of the author to make clear whether repetition is permitted. Your request is a result of the failure of the author of your textbook to do that.
    – N. F. Taussig
    Sep 9 at 19:41







1




1




On 1): the first digit must be $6$ or a $7$ (so $2$ choices). For the second and third there are $5$ choices. So $2times5times5$ numbers in total.
– drhab
Sep 9 at 17:19




On 1): the first digit must be $6$ or a $7$ (so $2$ choices). For the second and third there are $5$ choices. So $2times5times5$ numbers in total.
– drhab
Sep 9 at 17:19












@drhab Note: Please explain me how can I guess whether a question involves repetition or not,in general not only on this specific question.I already know how to solve this question.
– J.Doe
Sep 9 at 17:21




@drhab Note: Please explain me how can I guess whether a question involves repetition or not,in general not only on this specific question.I already know how to solve this question.
– J.Doe
Sep 9 at 17:21




1




1




Sorry, but I cannot really help you with that. Also for me every time I encounter a problem in that context I must wonder: "what exactly is allowed and what is not?" Others will have that too, and it might explain why your question on that has not been answered.
– drhab
Sep 9 at 17:23





Sorry, but I cannot really help you with that. Also for me every time I encounter a problem in that context I must wonder: "what exactly is allowed and what is not?" Others will have that too, and it might explain why your question on that has not been answered.
– drhab
Sep 9 at 17:23





1




1




I suspect that in both questions repetition of digits is not permitted since the questions do not explicitly state that repetition is permitted. In the second exercise, you may use each digit the number of times it appears in the list.
– N. F. Taussig
Sep 9 at 17:46




I suspect that in both questions repetition of digits is not permitted since the questions do not explicitly state that repetition is permitted. In the second exercise, you may use each digit the number of times it appears in the list.
– N. F. Taussig
Sep 9 at 17:46




1




1




It sounds like you would benefit from reading a more carefully written textbook. It should be the responsibility of the author to make clear whether repetition is permitted. Your request is a result of the failure of the author of your textbook to do that.
– N. F. Taussig
Sep 9 at 19:41




It sounds like you would benefit from reading a more carefully written textbook. It should be the responsibility of the author to make clear whether repetition is permitted. Your request is a result of the failure of the author of your textbook to do that.
– N. F. Taussig
Sep 9 at 19:41















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