"Breaking a number up into its powers of ten" is precisely what 'dec2base' and 'sprintf' undertake to do, except that the results are expressed in character strings rather than numerical digits.
However, it sounds as though you want to understand the techniques involved in this. To simplify matters suppose x is a non-negative integer and you wish to find the decimal digits that are used to express its value. Here is one technique that starts from the least digit and works up from there.
d = [];
b = true;
while b
r = mod(x,10);
x = (x-r)/10;
d = [r,d];
b = (x~=0);
end
