I have a clock in myhouse, on the wall.
On a summer's day I forgot to wind it and it stopped. Then I went to visit a friend who had a watch that was always right on time. After I stayed for a bit, I went home, made a simple alteration and set the clock just right.
Now how did I do this when I had no watch on me to tell how long it took me to come back from my friend's place?
Before I left, I wound the wall clock. Upon my return, the amount of change that I could see in the clock is how long it took to go to my friends place and come back, adding to that the time I spent there, which I know because the clock at my friend's place is accurate.
Subtracting the time of the visit from the time I was absent from myhouse, and dividing by 2, I obtained the time it took me to return home. I added this time to what my friend watch showed when I left, and set the sum on my wall clock.
If there is a Yellow house on Bluebird Lane, a Green house on Orange Street, a Pink house on Kitten Road, a Black house on Whitehorse Pike and a Purple house on Firebird hill, where is the White house?
I know what my job is, The point has been made. You say I have a big head, And you're right, I'm afraid. Put me in my place, And then leave me alone. What I need most, Is someone to drive me home. What am I?