How are zeros with exponents handled?
In scaled integer arithmetic, zero need not be treated as a special case; just like some other numbers, redundant encodings are allowed. All numbers with a coefficient of zero and with any exponent are valid, and (of course) they all have the value zero. (0 × 105 is zero.) These permitted redundant encodings of zeros mean that, very importantly, the exponent is independent of the coefficient in all calculations which are not rounded. For instance, consider subtraction. The rule here is simply that the exponent of the result is the lesser of the exponents of the operands and the coefficient of the result is the result of subtracting the coefficients of the operands after (if necessary) aligning one coefficient so its exponent would have the result exponent.
