There is a required calculator for Math 120, 124, 125 and 126.
It is the Texas Instruments TI-30X IIS which can be purchased from
many places for well under $20. The UW Bookstore carries orange ones,
which they will buy back at the end of quarters, but any color is acceptable
for Math 120, 124, 125 and 126.
is a picture of a black (the most common color) TI-30X IIS for reference.