My daughter had this question on her math homework for this week:
There is a 20 foot wall. A snail crawls up it. It crawls up 5 feet each day, but then slides back down 4 feet each night. How many days until it reaches the top of the wall?
My daughter initially put down 25. So I looked at it with this expression: 
She said, :smack: , I meant to put 20 days. Ok. I can see where she’d get that answer. But it’s not the answer I’d get.
What answer do you get?
I’m gonna go with 16 days.
17? Because after 16 days, it would have traveled 15 feet – so it would travel the final five feet on the 16th day, and, it being at the top, wouldn’t slide down.
I say he’ll reach the top on the 16th day, but slide back down to the 16ft level, because he would have slid down to the 15ft level on the 15th day and climbed up 5 feet to the top on the 16th day.
Oh, wait …
:smack:
16 days. Do I win a prize? Please? 
This is an old chestnut that around when I was in elementary school 35-40 years ago. It’s more of a reasoning problem than a math problem. I saw it in puzzle books but never on a legit math test.
I agree. I don’t see any way to do this that really involves much math. At least not serious math, if you know what I mean.