https://mathweb.ru/allsystem.html?id=167025

Умножить FFFFFFFFFFFFFFF0000000000000000(16) на FFFFFFFFFFFFFFF0000000000000000(16) = FFFFFFFFFFFFFFE00000000000000100000000000000000000000000000000 Столбиком

Введите два числа и укажите их основание системы счиления:

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Ответ: FFFFFFFFFFFFFFF0000000000000000₁₆ * FFFFFFFFFFFFFFF0000000000000000₁₆ = FFFFFFFFFFFFFFE00000000000000100000000000000000000000000000000₁₆