rang the bell.

[jasen]

A man enter a room. In the room there is a 2 digits number on the wall.
His friend outside the room do not know the number.
But just by ring the bell once, his friend know the number.
how could this happen ?

[TimeSpaceLightForce]

 

Spoiler

If their watches were not taken..the friend outside would know its no.99 when the bell rings after 1:39 pm.

 

[tpoulsen]

If the bell stated "You rang the bell at room ##", he would know

[BobbyGo]

Spoiler

Is it some strange hotel where the room numbers are posted inside the rooms but not in the hallway/outside?  If the friend is told to meet the man in room ##, he would only know if he was ringing room ## after his friend answered the door.

 

[TimeSpaceLightForce]

Spoiler

If the man inside the room rang the bell for 99 seconds..his friend would know Its no.99

 

[kaity7]

The number is either 10 or 12. They are the only 1 syllable 2-digit numbers, so he rang the bell once to show it was a 1 syllable number. Just guessing!

[jasen]

Ok, maybe my question is not specific enough.

- There is only one room, not hotel.
- The man inside the room, is giving information to his friend outside the room, by pushing the bell button once.
- there is only 1 bell, and it just ring, not stated something.
- The man inside the room, can't control how long the bel ring.
- the number is between 0 and 100.

[plainglazed]

perhaps...

Spoiler

the room was a bakery, or deli, or butcher, or the like with one of these:

so the friend outside heard the baker yell the number before his friend inside rang the bell to be served???

 

[jasen]

I was inactive for 4 days.

@TimeSpaceLightForce

Using time is the right answer, but they don't need that long. If they can measure the time accurately, both using accurate watch, the first man can inform the number not more than 2 minute.