Another thing I posted, my favorite example of real life unsconscious math:

> That's a great example of real life motivation. Now.... if only people came
> up to us on street corners with calculus problems that urgently needed
> solving....

Hey Betsy, you've stumbled onto one of my most favorite real life math examples. :-)

Suppose you're standing on the street corner, and you want to get to the other side. There are no lights, just an intersection. What do you do?

First you look one direction, see if any cars are coming, and if one is, you quickly estimate its speed (you know the direction). Then you look the other direction, same thing. Some time has elapsed, so you glance back in the first direction to confirm your estimate of that car's velocity (Has it traveled the distance you expected? Changed its velocity?).

Now. You decide. Calculate, or something. Will those cars intersect with your path if you start walking (assuming your own walking velocity, too)?

If the answer is that they will intersect, or your estimate is that they will come close to intersecting, you stay put. If the answer is that they will not intersect, you walk across.

You have done fairly complex math in your head, spur of the moment, on the spot. Important math, because inaccuracy could lead to getting squished. Can't get much more urgent than that.

And you do it, nearly effortlessly, *nearly every single day*.

Some people probably wait until there are no cars, because they have no confidence in their ability to figure out if things will intersect. Parents generally assume children can't do the math, and make them wait until an adult has done it.

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