A math-themed costume serves as alternative to the run-of-the mill witches, ghosts and princesses that appear every Halloween. Create a straightforward costume such as a calculator, or opt for wordplay, alternating the definitions of "pi" and "pie" for a bit of math-related humor. Keep wearability in mind when creating your costume; if you plan to sit or walk around a lot while wearing it, make sure the costume flexes or conforms to your position.
A Slice of Pi
Pi and pie, paired together, serve as costume themes based on a play on words. Craft a round costume from two large cardboard discs for the front and back of the outfit. Secure the two together, sandwich-board style, with straps or belts and hot glue. The straps go over your shoulders like suspenders, with the cardboard discs hanging in the front and back. Paint or use markers to decorate the cardboard to look like a pie with a slice missing, and draw a pi symbol on the pie. For a simpler variation, use two pieces of white foam-core board instead of cardboard discs. Draw a pie chart on the front and back costume panels, using a different color for each section of the pie. Label each color with the pi symbol -- the costume becomes a pi chart instead of a pie chart.
Do the Math
Craft a calculator costume for an instantly recognizable outfit. The simplest method is to print a calculator design on a T-shirt with an iron-on transfer designed for printers, or have a shirt printed for you at a screen-printing shop. A rectangular cardboard becomes a calculator costume when you cut armholes in the sides and a head hole in the top, leaving the bottom open for your legs. Paint the entire box to look like a calculator, with the keypad and display on the front. For a functional calculator costume, cut a slit in the front of the box instead of painting on a keypad. Slide the front flap of a tablet computer cover through the hole so the tablet hangs over the front, running a calculator app. Secure the flap to the inside of the costume with painter's tape, using additional bits of painter's tape or hook-and-loop tape to hold the back of the tablet cover to the box. Check the tablet frequently while wearing the costume to ensure it doesn't slide out.
Decorate an oversized T-shirt with your favorite odd number, such as 3, 7 or 9, using permanent markers or fabric paints. Wear mismatched clothing in bold colors or prints along with the T-shirt, including mismatched shoes and socks with at least one pant leg tucked into its respective sock. Toy plastic glasses decorated with bits of tape enhance the quirkiness of the odd number costume. Enlist friends to dress as other odd numbers for added entertainment value.
Dress the costume recipient in pants and shirt of matching colors and hold a tape measure or yardstick next to them, marking every 2 or 3 inches from the ground up along one pant leg and up the shirt with a marker or a bit of painter's tape. Write out each foot on the tape using a pencil or pen to plot out the design for a yardstick costume. Decorate the entire outfit with straight strips of painter's tape or with fabric paints, recreating the look of a yardstick, without anyone wearing the outfit as you work. Setting the clothes on a work surface allows you to use a yardstick or straightedge to create straight lines with paint or tape. Spell out the markings for each foot in large numbers with paint or tape.