if scale >= int32(Nano) {
			shifted := num + denom

			var value int64
			value, err := strconv.ParseInt(shifted, 10, 64)
			if err != nil {
				return Quantity{}, ErrNumeric
			}
			if result, ok := int64Multiply(value, int64(mantissa)); ok {
				if !positive {
					result = -result
				}
				// if the number is in canonical form, reuse the string
				switch format {
				case BinarySI: