shift value.
shifted number.
auto price = Decimal(123456, 3); assert(price.addExponent(0) == Decimal(123456, 3)); assert(price.addExponent(1) == Decimal(1234560, 4)); assert(price.addExponent(2) == Decimal(12345600, 5));
auto price = Decimal(-123456, 3); assert(price.addExponent(0) == Decimal(-123456, 3)); assert(price.addExponent(1) == Decimal(-1234560, 4)); assert(price.addExponent(2) == Decimal(-12345600, 5));
Add exponent and shift mantissa.