[Mike Betts]

I tend to agree with the venerable Mr. Flowerday. Don't memorize. Train yourself to look it up. It eliminates problems which creep in from a faulty memory.

As one of my old college professors put it, "You don't get partial credit if the bridge falls down".

Having said that, I do tend to know a lot of constants "approximately". It's nice to estimate what your answer should be and know that it's a good ballpark number.

Mike