All sorts of things, actually. Algebraic topology, homological algebra, algebraic geometry . . .
The easiest model I can think of is a reflection in the plane. Doing nothing is 0; reflecting across the y-axis once is 1; reflecting again is 1+1, but that's just the same as doing nothing, so 0.
You can get a slightly more complicated model which allows for addition AND multiplication, in which case 1+1 = 2 = 0, 1+1+1+1 = 4 = 0, 1+1+1+1+1+1 = 6 = 0, so 2 x 4 = 0 x 0 = 0 = 6 ;)
no subject
The easiest model I can think of is a reflection in the plane. Doing nothing is 0; reflecting across the y-axis once is 1; reflecting again is 1+1, but that's just the same as doing nothing, so 0.
You can get a slightly more complicated model which allows for addition AND multiplication, in which case 1+1 = 2 = 0, 1+1+1+1 = 4 = 0, 1+1+1+1+1+1 = 6 = 0, so 2 x 4 = 0 x 0 = 0 = 6 ;)