For College Algebra for Business and Calculus for Business:  A graphing calculator. (Exception: My online version of Calculus for Business prohibits graphing calculators and requires a scientific calculator.)
    If you do not already own a graphing calculator, buy a TI-83.  It sells for about $90 and can be obtained at many chain stores including Office Max, Office Depot, Best Buy, etc.  There is a similar (but more expensive) calculator called the TI-83 plus.  This calculator is also fine, but not necessary.  I will be using a TI-83 in class and if you have the same calculator it will be easier to follow along. The new TI-84 plus is essentially the same calculator as the TI-83, so it is fine.
     If you already own a TI-83, TI-86, TI-89  TI-92 plus or a Casio CFX-9850 GB PLUS, you are fine.  If you own a TI-82, TI-92 , TI-85, or an HP 48G or HP 48GX,  you do not need to buy a new calculator, but you will have to enter programs into your calculator that will enhance its capabilities.   I will be able to provide instruction on use of the TI-83, TI-83 PLUS,  TI-84 PLUS, TI-89, TI-92, and TI-92 PLUS.  Students with other calculators mentioned above are on their own as far as learning how to use them.

For College Algebra, Trigonometry, Precalculus, Geometry for Education, Calculus I and Calculus II: A scientific calculator.
    Graphing calculators are prohibited.  A cheap ($9-$20) scientific calculator is all you need.  If you are not sure how to tell if a calculator is scientific, it must have a key labeled SIN to be scientific. The only scientific calculators that you may not use are the Casio FX-300ES and the TI-30XS MultiView calculator.

For Social Choice Math and Finite Math: A calculator with a square root button.
   Graphing calculators are prohibited.  Scientific calculators are permitted, but not required.

For Differential Equations: No calculators permitted. (Sorry, it is a departmental policy.)