In the hexadecimal, binary, and octal number systems, Calculator displays only the lower digits of an answer when the result has more digits than your display size allows. This behavior mimics the way calculations work in computers.
For the hexadecimal number system, QWORD results can contain up to 16 digits, DWORD results can contain up to eight digits; Word results can contain up to four digits; and Byte results can contain up to two digits.
For example, using the hexadecimal number system displayed as Word, the largest result you can generate is FFFF (equal to 65535 in decimal). If you double that number (FFFFx2), the answer is 1FFFE. This contains five digits, so Calculator will display only the lower four digits of the answer: FFFE.