Finding a number?!?!

[mjtnas]

You are addressing a letter to find a friend who has just moved to another city, but you have forgotten the apartment number. All you can remember is that it is a three-digit number containing 1,5, and 9. What order is mostlikely to be the correct one? (Hint: How are apartments usually numbered?) Remember, if you use the "look it up method," make sure the answer is correct. Show your work and/or methodology.

I am stumped but I think my ADHD has me overthinking this one. In addition, I have no idea how apartments are usually numbered other than sequentially.

 

[galactus]

If it is a three digit number containing 1, 5, and 9, then there are 6 ways these numbers can be arranged.

What number is most likely?. I don't know how apartments are numbered either. Apparently, there is some special scheme to apartment numbering?. I have never lived in an apartment so I don't know much about that either.

But, I can tell you that:
159, 195, 591, 519, 915, 951 are the possible numbers. If one were to choose a random number from 1 to 1000, then each of these numbers have equal probably of being chosen. It may be 159 because that is the only one that goes in ascending order.

 

[tutor_joel]

The only thing I can think of is that the first number is usually the level and the last two ,the unit on that floor, like in a hotel. Seems like we're missing some information here on apt numbering schemes. So, 159 would be a first floor apt, but are there 59 units? Seems like a high number. 915 would be on the ninth floor and unit 15. Seems reasonable, as does 519. So, 519 and 915 seem reasonable to me. Then, how many apt buildings have 9 floors?

This is simply my reasoning, I could be way off base here.

 

[LivingMath]

Apartment room numbering generally follows the same scheme used in hotels. The first digit (or digits) is the floor number and the last two digits are the unit number. eg. 519 is the nineteenth unit on the fifth floor; 1206 is the sixth unit on the twelfth floor.

Generally speaking, apartments on lower floors will be more common than those on higher floors, and lower unit number will be more common than higher unit numbers, but which is more significant, lower floor number or lower unit number?

A search on Google for the term "apt. 159", and for each of the other possible value gives the following number of hits:

159 - 34,700
195 - 22,300
519 - 10,100
591 - 613
915 - 11,000
951 - 649

Even assuming there is a lot of noise in the Google results, the large margin of victory for Apt. 159 and Apt. 195 suggests that floor number is the most important factor, so we can be reasonably safe saying that 159 is the most likely number.