Calculators are commonly used at every education level. Calculators that can perform statistical or scientific calculations, manipulate matrices, and plot functions on a graph are particularly helpful in the study of higher-level mathematics. Although most scientific or graphing calculators are not accessible to someone who does not have usable sight, there are options available that allow students who are blind to use these tools successfully.
A number of talking scientific calculators are available on the market, although no single calculator may function as needed at all educational levels. This means that an assessment of the features needed by the student must be done to ensure that the best calculator for him or her is selected. Susan Osterhaus at the Texas School for the Blind has compiled a review of the functionality of various talking scientific calculators  which may help in the selection process.
Another option is to use a portable electronic notetaker with advanced math functions. Some notetakers combine speech synthesis and refreshable Braille that can be used by students who are blind for performing trigonometric and logarithmic calculations. Check with the notetaker manufacturer to see if a scientific calculator function is supported.
There is also software available which can provide speech access to a scientific calculator application. Some of these emulate a common calculator interface, and some can also provide audio access to graphs. The Audio Graphing Calculator (AGC)  is an example of an accessible Windows-based software program that features a graphing calculator capable of displaying graphs both visually and audibly as a sonified tone graph.
For additional information on access to scientific and graphing calculators see the resource Accessible Calculators  from the GeorgiaTech Center for Assistive Technology and Environmental Access (CATEA).
To find out more about accessible math consult the Knowledge Base articles What are some techniques for creating Braille math materials?  and Why is accessible math important? 
-  review of the functionality of various talking scientific calculators
-  Audio Graphing Calculator (AGC)
-  Accessible Calculators
-  What are some techniques for creating Braille math materials?
-  Why is accessible math important?