https://mathweb.ru/allsystem.html?id=159121

Сложить 0000000000000000000000000000000000000000000000100000000000000000(16) и 00000000000000000000000000000000000000000000001fffffffffffffffff(16) = 2FFFFFFFFFFFFFFFFF Столбиком

Введите два числа и укажите их основание системы счиления:
+0000000000000000000000000000000000000000000000100000000000000000
00000000000000000000000000000000000000000000001fffffffffffffffff
00000000000000000000000000000000000000000000002FFFFFFFFFFFFFFFFF
Ответ: 000000000000000000000000000000000000000000000010000000000000000016 + 00000000000000000000000000000000000000000000001fffffffffffffffff16 = 2FFFFFFFFFFFFFFFFF16