Answer :

AL2006

Most people let the three numbers be  x, x+2, and x+4, 
then add them up, set the sum equal to 156, solve the
equation for 'x', then calculate x+2 and x+4.

But I do it like this:

Three numbers have the sum of 156.
If all three were the same number, it would be  156/3  =  52.
Great !
Put  52  on the table three times.  Their sum is  156 .
Take  2  away from one of them.  It becomes  50.
Give the  2  to a different one.  That one becomes  52.
All you did was move a 2  around.
But now you have  50,  52,  and  54  on the table.  Their sum is still  156.