The one thing I remember from this is dimensional analysis. An awesome tool. You can use the units of the inputs to make sure that the output makes sense (e.g.

The one thing I remember from this is dimensional analysis. An awesome tool. You can use the units of the inputs to make sure that the output makes sense (e.g. if there's seconds in the numerator, and seconds*2 in the denominator, the result should have a unit of seconds). You can also use it to help remember a formula that you forgot part of.