YOU'VE BEEN ASSIGNED TO SPRAY-PAINT PLAYER NUMBERS ONTO SIX SPORTS JERSEYS. YOU'VE BEEN GIVEN TEN STENCILS, NUMBERED ZERO THROUGH NINE. ASSUMING EACH JERSEY HAS ROOM FOR TWO UPRIGHT DIGITS, WHAT'S THE LEAST AMOUNT OF STENCILS YOU NEED TO MAKE SIX UNIQUE NUMBERS?