The Student Room Group
Uni students - Complete our survey >>
Uni students - Complete our survey >>
Uni students - Complete our survey >>

Combinations on a combination lock

If I took a 10 digit, 3 letter combination lock where the combination could include 1 to 13 digits, would the number of possible combinations be
13C1 + 13C2 ..... + 13C13
Reply 1
Avatar for joostan
joostan
13
Original post by jsmith6131
If I took a 10 digit, 3 letter combination lock where the combination could include 1 to 13 digits, would the number of possible combinations be
13C1 + 13C2 ..... + 13C13


I don't think so.
Order's important in a combination lock - it's actually a permutation lock but hey ho::tongue:
I'm not 100% but the numbers and letters are independent of each other,
So there are 1010×263 10^{10} \times 26^3 ways of making a unique code, assuming you use all the units. Which is considerably larger than what you proposed at around 1.7576×10141.7576 \times 10^{14}
If you use fewer units as the code, it becomes more and more complicated :s-smilie:
(edited 10 years ago)
Original post by joostan
I don't think so.
Order's important in a combination lock - it's actually a permutation lock but hey ho::tongue:
I'm not 100% but the numbers and letters are independent of each other,
So there are 1010×263 10^{10} \times 26^3 ways of making a unique code, assuming you use all the units. Which is considerably larger than what you proposed at around 1.7576×10141.7576 \times 10^{14}
If you use fewer units as the code, it becomes more and more complicated :s-smilie:


On the lock I am referring to once the order in which the keys are pressed is NOT relevant!!
Reply 3
Avatar for joostan
joostan
13
Original post by jsmith6131
On the lock I am referring to once the order in which the keys are pressed is NOT relevant!!


There's still the possibility of choosing from 26 possible letters and the 10 digits etc.:colone:
Original post by joostan
There's still the possibility of choosing from 26 possible letters and the 10 digits etc.:colone:


no its a 0-9 and X,Y,Z combination lock

a207929133b2cb3489777e_m.jpg
Reply 5
Avatar for joostan
joostan
13
Original post by jsmith6131
no its a 0-9 and X,Y,Z combination lock

a207929133b2cb3489777e_m.jpg


Oh. Ok, if the order doesn't matter, are you allowed to hit the same button twice?
Original post by joostan
Oh. Ok, if the order doesn't matter, are you allowed to hit the same button twice?


no....i.e: if you do it makes absolutely no difference AND the code X739 = 973X.... it makes NO difference which ORDER you push the buttons
Reply 7
Avatar for joostan
joostan
13
Original post by jsmith6131
no....i.e: if you do it makes absolutely no difference AND the code X739 = 973X.... it makes NO difference which ORDER you push the buttons

In which case, I believe that you were right in your initial post and I've been wasting your time :tongue:

Quick Reply

Related discussions

Latest

Trending

Trending

Articles for you