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September 27th, 2017, 02:44 AM   #1
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Calculating the number of ways

How many codes can we create if we have to follow the conditions:
* Exactly two distinct numbers (0-9) must be used.
* Exactly two distinct letters (A-Z) must be used.
* The dot symbol (.) must be used exactly one time.
* The number zero (0) must not be in the leftmost position.
* The dot symbol (.) must not be in the leftmost position nor the rightmost position.
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September 27th, 2017, 03:09 AM   #2
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Originally Posted by Hussain2629 View Post
How many codes can we create if we have to follow the conditions:
* Exactly two distinct numbers (0-9) must be used.
* Exactly two distinct letters (A-Z) must be used.
* The dot symbol (.) must be used exactly one time.
* The number zero (0) must not be in the leftmost position.
* The dot symbol (.) must not be in the leftmost position nor the rightmost position.
What have you tried? Can you determine the number of ways given just one of those conditions?
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September 27th, 2017, 05:01 AM   #3
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What have you tried? Can you determine the number of ways given just one of those conditions?
Actually, I could not begin to solve this problem.
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September 27th, 2017, 06:36 AM   #4
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Can you give examples of such codes? And what is the required length of the codes?
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September 27th, 2017, 08:57 AM   #5
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Looks to me like length always = 5,
"lowest" code being 1.0AB
"highest" being 9.8YZ
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September 27th, 2017, 01:38 PM   #6
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Originally Posted by MATHEMATICIAN View Post
Can you give examples of such codes? And what is the required length of the codes?
If you read it carefully, you will see that the length = 5

Some examples: h.2c9
5c.2k
94y.s
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September 27th, 2017, 01:40 PM   #7
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Originally Posted by Denis View Post
Looks to me like length always = 5,
"lowest" code being 1.0AB
"highest" being 9.8YZ
The dot symbol can be used between the letters as well

Such as w.k27
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September 28th, 2017, 06:31 AM   #8
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Well, keep it simple.
Forget the "."
Calculate arrangements with 10 digits and 26 letters,
with exception being 9 digits in leftmost position.
Then multiply result by 3, since "." can only fit in 3 places.

As Grouchy Sir Joppy said: we don't give full solutions...
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