Hints for Solving Quantitative Problems

PRINCIPLES OF HYDROGEOLOGY
ESCI 337

Ten Easy Ways to Avoid Math Mistakes

1)  Draw a picture.

2)  Use good math punctuation.  (No arrows; no "stream of consciousness".)
Here's an example of bad math punctuation when finding the average
of three people's shoe sizes:     8.5 + 9.5 + 12 = 30 / 3 = 10

3)  Write the leading zero:  It's 0.12, not .12.

4)  Skip the Slash (/): Use a horizontal line when writing fractions.

5)  Love the units!  Trust the units!  They will reward you handsomely!

Write the units of measurement out at *every* step, even--and especially--when
working with units squared or cubed!

6)  Figure out how to enter 1 x 10-3 on your calculator using
 the ^ key, the EE key, and the xy key.

7)  Use parentheses, and Please Excuse My Dear Aunt Sally:

Parentheses
Exponents
Multiplication and Division (left to right)
Addition and Subtraction (left to right).

8)  If the measurement is squared, square the conversion factor.
If the measurement is cubed, cube the conversion factor.

9)  Check by simplifying.  Do the calculation again, this time using rounded
or approximate numbers.  Are you in the same ballpark?

10)  Does it make sense?  ("How big is it?"  "What's typical?")

Department of Earth Science | Northeastern Illinois University
5500 North Saint Louis Avenue, Chicago, Illinois, USA 60625
© 2011 Laura L. Sanders.  Last updated January 13, 2011.