Private Math Tutor

Ok, I've got a good one for you guys. Follow the following steps and you will get the number 9.

Pick some integer number (feel free to make it as large as you want), for this example, I'll use 123456. Now rearrange the digits in your number for some new number. So for example I'll rearrange mine as 526413. Now subtract the smaller of the two from the larger number. So, 526413 - 123456 = 402957. Now add each digit together. So I get 4 + 0 + 2 + 9 + 5 + 7 = 27. Now repeat this last step until you get a one digit number. So 2 + 7 = 9. :D This works most of the time, the alternative answer is 0 for some special circumstances where the number you pick is the same digit for the entire number (i.e. 111) or if your number is less than 10.

A boat has a ladder that extends 12 inches into the water. If the water level falls 10 inches and then raises 8 inches, how much of the ladder is in the water?