according to this definition. if i take one tire and melt another tire to it ( 1+1) then I'll end up with 1 tire. if you can change the size when adding them the addiction is correct according to the definition... so the true mathematics. Me and the neanderthal fell out today over this 😂😂 it's crazy how he can't understand his ancestors language and definitions. THE SUM OF THE SIZE/MASS DOES NOT CHANGE THE QUANTITY.