https://mathweb.ru/allsystem.html?id=340002

Умножить FFFFFFFFFFFFFFFF(16) на 0008000000000000(16) = 007FFFFFFFFFFFFFFF8000000000000 Столбиком

Введите два числа и укажите их основание системы счиления:

x																	F	F	F	F	F	F	F	F	F	F	F	F	F	F	F	F
x																	0	0	0	8	0	0	0	0	0	0	0	0	0	0	0	0
+																	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
																0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
															0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
														0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
													0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
												0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
											0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
										0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
									0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
								0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
							0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
						0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
				7	F	F	F	F	F	F	F	F	F	F	F	F	F	F	F	8
				0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
			0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
		0	0	0	0	0	0	0	0	0	0	0	0	0	0	0	0
		0	0	7	F	F	F	F	F	F	F	F	F	F	F	F	F	F	F	8	0	0	0	0	0	0	0	0	0	0	0	0

Ответ: FFFFFFFFFFFFFFFF₁₆ * 0008000000000000₁₆ = 007FFFFFFFFFFFFFFF8000000000000₁₆