BigFixed.resolution

auto b1 = BigFixed(0, 1).resolution;
assert(b1.toDecimalString(1) == "0.5");

auto b2 = BigFixed(100, 1).resolution;
assert(b2.toDecimalString(1) == "0.5");

auto b3 = BigFixed(100, 3).resolution;
assert(b3.toDecimalString(3) == "0.125");