You will need:
Cardboard or foam board
Number stencil (either printed from a computer and blown up to preferred size, or bought)
About 15 button mums (per number)
Hot glue gun and glue sticks
Remove stems from mums, cutting as close to the heads as possible without damaging the blooms. Stencil number on cardboard and cut out. Apply hot glue on back of mum head and affix to number, until entire background is covered. Let dry. Cut piece of ribbon and tie number to chair or place on table in prominent spot.