> Or maybe I already got the intuition they were trying to convey? If you pull out a calculator to multiply two 3-digit numbers and get back a 4-digit number,

> Or maybe I already got the intuition they were trying to convey? If you pull out a calculator to multiply two 3-digit numbers and get back a 4-digit number, are you going to trust the calculator or are you going to go "wait a minute..." and double check you entered it right? If the latter, you probably already have the intuition it's supposed to teach. Edit: Or for something a bit more every-day: You're at a store and buy something that costs $6.24, pay with a $20, and get back $6.62. You may not know exactly what you were supposed to get back, but you do immediately know without having to do the math that it was definitely more than that.