Math is an incredibly important part of architecture, and the study of basic physics, geometry, trigonometry and calculus is part of the curriculum at any architecture program.
That said, the day to day use of math, while constant, is usually pretty simple. I'd say the most common techniques used are fractions (for adding dimensions such as 1/8", 2-1/2", 2'-6"...) and area calculations (for square footages of rooms & buildings, to calculate how many people per space...). Some architects will use ratios for determining optimum sizes and dimensions in building relationships, others will employ complicated equations to produce curvy and crazy forms, but those things are not required for a normal days work, usually.
Engineers will always do the heavy lifting for structural calculations, HVAC fluid dynamics, and electrical loads, etc. etc.. An architect is not trained or licensed to do those things, and could actually get sued for doing so.
Mathematics is used by architects to express the design images on a drawing that can then be used by construction workers to build that image for everyone to see. Mathematics is needed to analyze and calculate structural problems in order to engineer a solution that will assure that a structure will remain standing and stable. The sizes and shapes of the elements of a design are possible to describe because of mathematical principles such as the Pythagorean Theorem.