What's the time on your watch?

$12 \times 10 = 120$

All we need to worry about is what time it is $123 - 120 = 3$ hours later.

$6 + 3 =$ $\boxed{9}$

after 24 hours the clock will show the same time . ie. if the clock start 6 o'clock after 24 hours it shows the same time 6 o'clock. 123= 24x5+3 24x5 = 120 (ie. after 120 hours the clock shows 6 o'clock.)

adding 3 hours to 6 o'clock

6+3= 9 o'clock.

As $123 = (12\times10)+3$ , you can expect the clock to turn to the starting position (which is 6) for 10 times and move 3 numbers forward, hence, after 123 hours, it will fall at the number 9.

123=3(mod12), 3+6=9

I honestly guesses 9 cause its really late and thought 24 not 12

It is a 12 hour clock therefore after 12 hours it will be 6 so in 123 hours no of 12 hours are 10 120h

123h-120h =3hours later =9 o clock

This is explanation

123 ≡ 3 (mod 12), 6+3≡ 9 (mod 12)

so it's 9 o'clock

123 ≡ 3 (modulo 12)

6 + 3 = 9

It's 9 o'clock.

$Frac(\frac{123}{24}) \times 24 = 3$

$6 + 3 = 9$

$123 \equiv 3\ (\textrm{mod}\ 12) \\ 6+3=9$

The time will be 9 o'clock.

Say for example it is evening at 6 o' clock.Now, as you know a day consist of 24 hours.Now after 24 hour next day the same timing will be there but the date will be changed.No matter about the date here.
Now think like this multiply 24 with that maximum number which is less than 123 .Ok, So you will get 120(24×5) that means 5 days.Now you have to subtract that 120 from 123.
123-120=3hrs .Now this means after 5 days you will have same time that is 6 o' clock.Now, you are left with 3hrs add this to 6 o' clock.
6+3=9 o' clock .