1. A method of computing comprising the steps of: providing a memory group, said memory group having one or more registers, said registers comprising a digital multistate phase change material, said phase change material having a plurality of states, said states including: a reset state, a set state obtainable from said reset state by applying energy in an amount corresponding to the set energy of said reset state, said set state having lower resistance than said reset state, and one or more intermediate states having substantially the same resistance as said reset state, said one or more intermediate states being obtainable from said reset state by applying energy in an amount less than said set energy of said reset state; performing a mathematical operation selected from the group consisting of addition, subtraction, multiplication, and division by providing energy to said one or more registers so as to effect transformations of said registers among one or more of said plurality of states.